Palms on the University of Arizona Campus
INTRODUCTION
Wherever one looks on the University of Arizona (U of A) campus, palm trees enter the view. Palms line the roadways and sidewalks and frame the doors of university buildings. With so many palms, they are often taken for granted and no one pays much attention to their diversity, or to their tremendous beauty. On the U of A campus alone, one can find as many as 25 species of palm trees, each with its own set of unique characteristics (although some look remarkably similar at first glance). The purpose of this report is to enlighten its reader about the palm family in general, and to facilitate easy identification of palms on the campus. The report is divided into three main sections. In the first section, I introduce the main features of the palm family, providing the context from which to understand palms in general. In the second section, I describe the Arecaceae subfamilies, as they are currently divided, and briefly discuss the current thought about relationships between different groups of palms. The third section deals specifically with the palm species found on the U of A campus. Here, I start with a key to the palms on campus and continue with species by species descriptions and a campus map which locates all the palm trees found on campus (This part expanded 2009).
ARECACEAE (alternately known as PALMAE)
Arecaceae belongs to its own order, the Arecales. The family is among the world’s larger plant families, both in terms of the number of species and in abundance (Henderson, et al. 1995). Estimates of the number of species and genera range from 2500-3500 and 210-236, respectively (Jones 1995). Variation in estimates emerges due to the use of different species concepts by different authors. Within the plant kingdom, palms stand out. Palms claim the largest seed – the double coconut of Lodoicea maldivica which weighs as much as 20 kilograms, and Corypha spp. boasts the largest plant inflorescence that exhibits a candelabra-like structure with as many as ten million flowers. Raphia regalis has the longest leaf in the plant kingdom – up to 25 meters long, and palms vary tremendously in height from 10-15 cm tall at maturity (Syagrus lilliputiana) to more than 60 meters (Ceroxylon quindiuense and C. alpinum) (Jones 1995). Palms also possess high ethnobotanical and economic value. They include major plantation crops, such as oil palm, coconut, and date palm, they are widely used for oil, wax, starch, fiber, sugar, alcohol, they provide a local source of food, thatch, fiber, wax timber, sugar, salt, beverages, medicine, and they have become increasingly important in commercial horticulture.
People usually associate palm trees with a humid tropical environment. Although palm species rarely grow in very dry or cold regions, almost all of the species found on the U of A campus originate in dry areas. For palms to grow in dry areas, they require a water source. In the wild they normally occur in oasis and canyon washes where ground water is present.
Palms exhibit wide variation in morphological feature, however they are easily recognizable by the common layman. Stem growth form varies widely from short to tall, robust to slender, and occasionally, swollen. Most palms have a solitary trunk, but some grow as clusters or even climbers. A few develop an underground trunk or a very reduced trunk and appear trunkless (Jones 1995). Leaf form may be pinnate, palmate, or seldomly bipinnate (only in the genus Caryota).
Flowers are borne in single to many-branched inflorescences subtended by bracts. These bracts vary from a single large bract to many smaller bracts which sheath the peduncle of the inflorescence. Individual flowers are generally small, born in dense clusters and usually whitish to yellowish in color, and may be unisexual or bisexual. Many flowers release odors to attract pollinators (Jones 1995). Traditionally, it was believed that all palms were wind-pollinated. Recent research, however, indicates the contrary. Uhl and Dransfield (1987:49) predict that "most palms will be shown to be insect pollinated, or that both wind and insects are involved". Pollen transfer by insects is frequent and diverse and involves flies (e.g., Nypa spp.), beetles (e.g., Orbignya, Bactris spp.), bees (e.g., Sabal palmetto, Iriartea spp.), and even moths (e.g., Bactris spp.) (Tomlinson 1979, Uhl and Dransfield 1987). Most palm fruits are fleshy drupes and vary significantly in size, shape, surface texture, and color. Fleshy fruits contain high amounts sugar or fat, providing a rich energy source for both humans and animal dispersers (Blombery and Rodd 1982). Very little is actually known about methods of dispersal in palms. Most fruits appear to be dispersed by animals, including squirrels, bats, birds, and rodents, while a few species produce fruits that are dispersed by water (e.g., Nypa fruticans, Cocos nucifera) (Uhl and Dransfield 1987).
Palms, like other monocots, posses no secondary vascular cambium, and therefore experience no secondary growth. All growth in palms occurs in the apical meristem which initially measures about one millimeter in diameter. The primary thickening meristem becomes progressively more broad before the stem elongates, hence establishing the tree’s diameter prior to upwards growth. The period of apical meristem expansion is known as the establishment phase, and may take several years.
Tomlinson (1979) offers a concise conspectus of the family Arecaceae:
Plants typically with woody self-supporting aerially unbranched trunks, rarely aerial branching dichotomous; if scandent, never root climbers; stem branching, if present, almost always basal and never branching distally below a terminal inflorescence. Leaves 2-, 3-, or usually many-ranked; leaf base (at least initially) a closed tubular sheath, blade well-developed, on a longer or shorter petiole with a single midrib or rachis; the blade plicately folded with a marginal nonplicate strip, usually split partly or completely into leaflets (pinnate leaves) or leaf segments (palmate leaves). Shoots usually pleonanthic, but hapaxanthy (sometimes leading to monocarpy) occasional. Flowers sometimes perfect, but usually diclinous by abortion and plants monoecious or dioecious. Lateral inflorescences (or first-order branches of terminal inflorescences) typically much-branched with a basal prophyll and one or more enlarged basal (but never petaloid) bracts, the distal bracts reduced. Axis rarely unbranched as a true spike (=spadix). Single inflated (sometimes woody) enveloping bract (=spathe) if present never on the trunk axis. Flowers either solitary or more usually aggregated in 2s, 3s, or more, the aggregations commonly representing condensed cincinni. Flowers typically with 3, 6, or sometimes more numerous stamens, gynoecium apocarpous with 1-3 carpels or more commonly syncarpous with 3 (sometimes more) locules each with 1 functional ovule, 2 locules and ovules sometimes aborted. Fruit almost always indehiscent, baccate, or drupaceous 1-3-several-seeded, the pericarp woody, fleshy or fibrous, the endocarp sometimes thick and woody. Endosperm abundant (usually of hemicellulose), embryo small, germination hypogeal.
Palms Classification and Relationships
Early taxonomic literature on palms began with C.F.P von Martius’ Historia Naturalis Palmarum (1849-53), followed by monographic series of the Italian botanist Beccari in the early 1900s. L. H. Baily also wrote many important palm monographs in the early 1900s. Since then, H. E. Moore has carried out the most extensive taxonomic research on palms(Tomlinson 1979). Uhl and Dransfield (1987) build upon on his work after his untimely death in 1980, bringing together the most current and extensive information about palms in the book Genera Palmarum (Uhl and Dransfield 1987).
Until very recently, palms were classified into fifteen major groups defined by Moore: Arecoid, Borassoid, Caryotoid, Ceroxyloid, Chamaedoreoid, Cocosoid, Coryphoid, Lepidocaryoid, Nypoid, Phoenicoid, Iriarteoid, Podococcoid, and Geonomoid (Blombery and Rodd 1982, Tomlinson 1990). This classification relies mostly on gross morphological characteristics, such as induplicate or reduplicate, and fan or feather leaves. Vegetative and floral anatomy supports Moore’s subdivision of the Arecaceae based on morphology (Tomlinson 1990). These groups have since been slightly reorganized into six subfamilies within the Arecaceae: Coryphoideae, Calamoideae, Nympoideae, Ceroxyloideae, Arecoideae, and Phytelephantoideae. The following gives a synopsis of these subfamilies and their most important features. The information is adapted from Uhl and Dransfield (1987).
I. Coryphoideae -
The Coryphoideae make up the most diverse subfamily within Arecaceae and includes more unspecialized characters than any other subfamily. The subfamily is split into only three tribes, Phoeniceae, Corypheae, and Borasseae. Palms in Coryphoideae exhibit high variation in leaf form, although they are usually distinguishable by a palmate or costapalmate (induplicate) leaf. Inflorescences are subtended by numerous peduncular bracts, or one, or none. Flowers are predominantly solitary, or in irregular or regular cincinni with a gynoecium of predominantly three, sometimes four, carpels, apocarpous or syncarpous. All apocarpus palms belong to the Coryphoideae, except for those of Nympoideae. Normally fruits develop from just one carpel, and spines, where present, are petiolar.
II. Calamoideae -
The subfamily Calamoideae has 22 genera and includes the climbing palms (e.g. Desmoncus,Oncocalamus). Calamoideae palms have pinnate leaf form, reduplicate in veination, or rarely palmate leaf form, and exhibit several shared derived characters: emergent spines on various organs; predominantly tubular inflorescence bracts and floral bracteoles; special climbing organs, the cirrus (extension of the leaf rachis bearing reflexed spines) and the flagellum (modified inflorescences lacking flowers and branches and bearing dense reflexed spins on the peduncular bracts); dyadic flower clusters; fruit and ovary covered with distinct overlapping scales; tri-locular and tri-carpellate gynoecium in which the ventral sutures of the carpels are not completely closed; and the micropyles of the anatropous ovules face the center of the gynoecium. The last three characters occur in no other Arecaceae subfamily. The only clear relationship that Calamoideae shares with any other subfamily are with the Coryphoideae: several to few or no peduncular bracts; trimerous gynoecium; and the loss of two carpels after fertilization.
III. Nypoideae -
The Nypoideae contains only one genus, Nypa, which has large reduplicate pinnate leaves. These palms display unusual inflorescence, flower and fruit structure. Nypoideae produces floating fruits, and its unusual inflorescence is terminated by a pistillate head with lateral branches ending in short spikes of staminate flowers. Furthermore, these palms develop a dichotomously branched stem, unlike any other subfamily. According to Uhl and Dransfield (1987), the regular pinnate leaf of this subfamily is the only structure which indicates a relationship with other palms (i.e. Calamoideae, Ceroxyloideae, Arecoideae, and Phytelephantoideae).
IV. Ceroxyloideae -
The subfamily Ceroxyloideae includes 11 genera, and includes palms with pinnate reduplicate leaves. Flowers are moderate to small, solitary and spirally arranged, or in special cincinni, and display valvate, distinct, or connate sepals and petals, and a tri-carpellate syncarpous gynoecium. Palms have several peduncular bracts, spirally arranged, and relatively small fruits developed from one carpel resemble some less specialized Coryphoideae. Some species possess incomplete prophylls and/or multiple inflorescences which suggests a relation to the Arecoideae.
V. Arecoideae -
The Arecoideae subfamily contains six very diverse tribes. In all groups, flowers are arranged in triads of a central pistillate and two staminate flowers, or flower clusters derived from triads. Leaves are pinnate or bipinnate. Each tribe displays the following characters:
- Caryoteae and Iriarteeae: several peduncular bracts, praemorse leaflets, induplicate leaves, tri-carpellate gynoecium, some with multiple inflorescences, bipinnate leaf form.
- Podococceae: one genus, three peduncular bracts, leaf structure similar to Iriarteeae.
- Areceae: usually one or two peduncular bracts and pseudomonomerous gynoecium, valvate petals in staminate flowers, extremely imbricate petals in pistillate flowers.
- Cocoeae: usually one or two peduncular bracts, trimerous gynoecium, endocarp with pores, valvate petals in staminate flowers, extremely imbricate petals in pistillate flowers.
- Geonomeae: usually two peduncular bracts, spicate inflorescence branches bear highly specialized flowers enclosed in pits.
VI. Phytelephantoideae -
The Phytelephantoideae subfamily, made up of three tribes, exhibits distinct monopodial flower clusters. This subfamily is monoecious, and flowers contain a five to ten connate carpellate gynoecium (also found in three genera of Arecoideae). The flowers normally display more than three parts per whorl (this only occurs outside the Phytelephantoideae in one genus belonging to the Coryphoideae), and centrifugal stamen development. Palms in this group also produce many-seeded, multiparted fruit. Phytelephantoideae develop two fully developed peduncular bracts along with many small ones.
In terms of cladistic analysis, Uhl and Dransfield (1987:68) argue that "no one shared derived feature characterizes all genera of Coryphoideae. Perhaps this family, including as it does a majority of the least specialized characters in the family as a whole, represents in part relicts of an earlier more widespread palm population. Each of the other five subfamilies is characterized by one or several shared derived characters and each appears to represent a natural and monophyletic group of genera."
Tomlinson (1990) proposes an evolutionary trend in the Arecaceae as tending towards reduction in number of inflorescence branch orders; reduction in number of large, proximal bracts, tending towards those with few or even two or one basal enveloping bract; and evolution from sexual specialization of different parts of inflorescence to different inflorescences on same plant, to dioecious.
Few extensive phylogenetic studies of the Arecaceae exist at present. In recent years several studies have emerged attempting to fill this gap. Zona (1997) performed a cladistic analysis of Arecaceae genera from the sub-tribe Ptychospermatinae of the Arecoideae sub-family which are native to Australia and Southeast Asia. The author found unsuspected intergeneric relationships. One genus was discovered to be polyphyletic while a single species was unrelated to other taxa within its genera. A study by Lewis, et al (1997) examined the alliance between two sub-tribes, Oncospermatinae and Iguanurinae, within the Arecoidae sub-family. They found the subtribe Oncospermatinae to be paraphyletic and at least two of the genera of Iguanurinae nested in the Oncospermatinae clade. Baker, et al. (1997a) explored the systematics the Calamoideae, the subfamily that displays the greatest range of morphological diversity. Despite this diversity, the group resolved as monophyletic based on a combination of characters – morphology, chloroplast DNA restriction site data, and chloroplast DNA sequence data. Their study uses morphology and nuclear DNA sequence data to explore the relationships among 22 genera within Calamoideae. Baker, et al. (1997b) investigated the relationships between subfamiles and tribes with chloroplast DNA from 60 genera representing all subfamilies and tribes. This study showed that the monophyly of Calamoideae is strongly supported, Ceroxyloideae is paraphyletic although two or three of its tribes seem well-resolved, Coryphoideae exhibited no support for monophyly, and the relationships of Arecoideae are uncertain but the subfamily may be linked to Ceroxyloideae and Phytelephantoideae. Asmussen and Doyle (1997) also used chloroplast DNA restriction site data and sequences from rbcL, the intron, and intergenic spacer to show that the palm chloroplast genome is conserved in comparison with other families. They conclude that the rpl16 intron is a promising source of characters at the genus, tribal, and subfamily levels.
The evidence from this handful of studies suggests that the current classification of Arecaceae needs more work. Furthermore, the wide use of chloroplast DNA in the cladistic analysis of these studies may confuse the phylogeny if hybridization and/or introgression occurs because of the maternal inheritance factor. Evidence of hybridization in Orbignya x teixeirana Bondar (Balick 1988) and among Phoenix spp. (Muirhead 1961) suggests the need for further research on this topic and provides a subtle warning to those using chloroplast DNA data. Other characters, such as non-organellar DNA and molecular or chemical data, may prove to be more useful in determining the phylogenetic relationships among palms.
PALMS ON THE U of A CAMPUS: Palms can be seen throughout the U of A campus. Almost every building has at least one palm tree in the near vicinity. The library alone is surrounded by ten species. In the following pages, sixteen palms found on the U of A campus are pictured and described. The palms are organized in alphabetical order. I provide a morphological description of each and ethnobotanical information when available. Each species name links to a descriptive page.
Descriptions of Palm Species found on Campus: 25 different species from the family Arecaceae occur on the U of A campus. The majority (13 species) belong to the Coryphoideae subfamily, although three palms belong to the Arecoideae subfamily. Table 1 summarizes the main morphological characteristics of each palm, including family, subfamily, tribe, and subtribe, as well as the common name. The summaries provide a more detailed information about palm morphology, general characteristics of the genus, place of origin, habitat, and ethnobotanical uses. They also indicate distinguishing features of each species which can lead to quick identification, and one or two sample locations where the species can be seen.
ACOELORRHAPHE - This genus has only one species (a monotypic genus). It is native to the brackish lowlands of Florida and the Caribbean. It is monoecious, having separate male and female flowers on the same plant. A clumping palm that can grow to 3-5 meters tall and wide, Acoelorraphe is suited to hot humid regions.
1. Acoelorrhaphe wrightii - Origin: Caribbean region. Common name: Everglades palm, Paurotis palm. The only species within the genus has spherical leaf crowns that contain 10-16 leaves. As the slender stems mature, they are ringed with leaf base scars. The palmate leaves are semi-circular, 1 m in diameter, on heavily armed 1 m petioles . Each leaf is segmented to more than halfway to the petiole, and each segment is again divided at the tip. Leaves are silver on the underside. Fruits are ovals, about 1.5 cm in diameter, and hang in clusters that ripen in summer.
Distinguishing features on the UA campus: Small individual, planted on north east corner of Palm Garden (NW of Education Bldg) by PL S 235 class in 2009.
BISMARKIA - The genus has one species - Bismarckia nobilis, native to Madagascar, where it grows in savannah woodland.
1. Bismarkia nobilis - Common name: Bismarck palm. Slow growing, massive single trunk. Height eventually up to 100 ft tall. Waxy blue foliage is made up of costa palmate leaves, each up to 10 ft across. The head, even on young palms can become 20 ft across. Blade is divided to about 1/3 and there are filaments between segments. Simple branched cream-colored inflorescences, ultimate branches thick and catkin-like. Dioecious - separate male and female plants. Speckled brown fruits are 1-1.5 inches long. This palm is relatively tender, but loves the summer heat. Tolerant of alkaline soils and bright conditions. Distinguishing features on the UA campus: Young palms – waxy blue.
BRAHEA (formerly Erythea) - The genus Brahea is made up of about 12-16 species native to Baja California, Mexico, and Central America. Members of this genus normally grow in colonies in open, rocky environments. Their leaves are shortly costapalmate with a bluish or pale green color and divided to about half their length into segments which are further subdivided. Trunks are usually solitary. Local peoples commonly use the leaves of Brahea for thatching.
1. Brahea aculeata - Origin: southern Sonora and adjoining states. Common name: Sonoran hesper palm. Single trunk to about 9 m tall and 20 cm in diameter. Fan shaped leaves can be 80 wide x 110 cm long and are bluish-green. Segments are narrow. Spiny petioles with yellow teeth are nearly as long as the leaf blades, although young plants have fewer teeth. Inflorescences of white flowers are slightly longer than the leaf blades, arching, then hanging heavy with the 2.5-3 cm fruits that ripen to golden brown.
Distinguishing features on the U of A campus: Three small individuals, planted into center of Palm Garden (NW of Education Bldg) by PL S 235 class in 2009.
2. Brahea armata - Origin: Mexico Common Name: Blue Hesper Palm, This palm has stiff, blue costapalmate leaves which hang when dead to form skirt (unless pruned, as is common on the U of A campus). It grows up to 12 meters tall with a trunk about 40-50 cm in diameter. Cream colored flowers in arching inflorescences reach four to six meters long, often extending beyond the leaves. The fruit (18-24 mm long) is ovid, shiny, and brownish-yellow with white stripes or speckles. B. armata is native to northern Baja California, north-western Mexico where the species grows in rocky canyons. (Jones 1995) The Yuman Indians grind the seeds of this palm into a meal for consumption. They also eat the fruit and use it for making beverages (Castettler and Bell 1951 in Balick, et al. 1990).
Distinguishing features on the U of A campus: Grayish-blue costapalmate leaves; long inflorescence extending to edge of crown or longer, infructescence heavy hanging down beyond leaves; thick cream-colored spines along petiole, often bifid. See in the Forbes Courtyard.
3. Brahea brandegeei - Origin: mid to upper Sonora. Common name: Babisa or Palmilla. Robust single trunk (25 cm) can grow 16 meters tall. Gray leaf bases remain attached. Petioles are have golden teeth, sometimes in twos. Fan shaped leaves are divided more than halfway to the base. They are varied in color, ranging from gray/blue to dull green on both surfaces, sometimes duller on bottom. Inflorescences can number from 10-12 on a tree, and are normally longer than leaves, up to 3.5 meters. Fruits are less than 2 cm long.
Distinguishing features on the U of A campus: Small individual, planted on south east corner of Palm Garden (NW of Education Bldg).
4. Brahea edulis - Origin: Mexico Common Name: Guadalupe Palm The trunk of B. Edulis is stout and grows 10-12 meters tall. Leaves measure one to two meters across and are divided to about ½ of their length into segments. At the apex, the segments are shallowly bifid. The inflorescence does not extend past the leaves while in bloom, but later enormous quantities of small (25-35 mm diameter) fruits weigh down the structure. Flowers appear whitish-green. The fruits are round and black with fleshy, sweet pulp which is edible (25-35 mm in diameter). The palm is native to Guadalupe Island where grows in deep, warm ravines. ( Jones 1995)
Distinguishing features on the U of A campus: costapalmate; bifid leaf segments; slender petiole with small white spines.
5. Brahea nitida - Origin: western Mexico. Common name: Babisa. Slender single trunk (30 cm), only to 10 meters tall. Unarmed petioles about 1 m long. Flat shiny leaves often wider than long (to 100 cm), with segments that divide to about half way. Underside can be dusty white. Notable is a slender curling fiber where segments divide. Branching inflorescences arch to about 2.5 meters, with flowers arranged in spirals. Inedible ripe fruits are orange and oval shaped, but only about 1 cm long.
Distinguishing features on the U of A campus: One small individual planted on north-west corner of Palm Garden (NW of Education Bldg) by PL S 235 class in 2009.
BUTIA - The genus Butia includes about eight species found in southern Brazil, Paraguay, Uruguay and Argentina. These palms often form colonies in savanna and sparse woodland. They are stout, solitary palms with prominent leaf bases retained over most of the trunk. Leaves are arching, feathery fronds with narrow, stiff petiole and leaflets. Spines or spiny fibers border the petiole margins, becoming shorter or absent in the upper part of the leaf stalk.
1. Butia capitata - Origin: South America Common Name: Pindo Palm This palm has a stout woody trunk which grows to five meters tall and 30 to 50 cm in diameter. Strongly arching, bluish-green pinnate leaves extend 1.5 to 2.5 meters in length, and long spines (8-11 cm) line the petiole margins with fibrous material between their bases. The leaflets are broader than in Jubaea and flatten towards the apex. B. capitata has yellow or reddish fruits, two to three centimeters in diameter, and somewhat flattened which are edible. (Jones 1995, Blombery and Rodd 1982).
Distinguishing traits on the U of A campus: Long pinnate leaves strongly inward-curved; persistent non-overlapping leaf bases; spines long and becoming fibrous toward base of petiole. See at the southern entrance to the Education Bldg.
CHAMAEROPS - The genus Chamaerops contains just one species. It grows in coastal and near-coastal environments, often on rocky headlands and low hills
1. Chamaerops humilis - Origin: Southern Europe, Northern Africa, Malta Common Name: European Fan Palm, Mediterranean Fan Palm This species may have one to many trunks and normally grows two to six meters tall. The palmate leaves are glaucous, green in color and deeply divided with each segment subdivided again the segment apex. Slender petioles are lined with conspicuous forward-pointing spines, and leaf base fibers usually cover the trunk. The palm displays short inflorescences which are dioecious, surrounded by a large tubular bract flattened in the upper part and with a pointed apex. Flowers are cream to yellow (male flowers tend to be more bright yellow and female flowers yellow-green), and the fruits appear yellow to dull orange or brown. C. Humilis leaves are used for weaving various crafts, such as baskets and hats, and for cordage, paper making, and the fibers crushed to make apolstry and mattress stuffing. During the late 1800s and early 1900s, these fibers, called "crin végétal", became an important export industry for countries in Northern Africa, such as Morocco and Algeria (Decampo 1933 in Balick, et al. 1990). Fibers from leaf sheaths are also used to weave carpets. Arab peoples eat the palm heart and unripe flowers of C. Humilis, and they use the palm as anti-diarrhea medicine. Buttons and beads are also made from the kernels (Richard 1933 in Balick, et al. 1990). C. humilis is the only palm indigenous to Europe. (Jones 1995, Blombery and Rodd 1982).
Distinguishing features on the U of A campus: Usually clustered stem 1-4 meters tall with fibrous bark; long narrow petiolar spines; slender leaf petioles, palmate leaf deeply divided into segments. Several located in the Shantz breezeway.
JUBAEA - The genus Jubaea includes only one species which is endemic to Chile where it grows in the Andean foothills and open hillsides.
1. Jubaea chilensis - Origin: Chile Common Names: - Chilean Wine Palm, Coquito Palm, Honey Palm This palm has a tall, solitary, massive, gray trunk patterned with wide, diamond-shaped leaf scars. Jubaeagrows to 25 meters tall with a diameter of one to two meters. The only specimen on campus is still young and approximately one meter tall. Its leaves are pinnate with narrow, stiff, leaflets consistently folded to the apex, and spread on one plane. This palm has short fibrous petioles. Inflorescences are large and pendulous, branched to one order, and surrounded by a single large woody bract. The fruits are brown and resemble miniature coconut. It grows in woodland and on rocky ridges. The species is native to Chile where it has become rare due overharvesting for its sugary sap which is distilled to make palm honey used in making wine and sugar. In order to harvest the sap, the tree must be felled. The kernels are also used to make confections (Helmsley 1906 in Balick, et al. 1990). (Jones 1995, Henderson, et al. 1995, Blombery and Rodd 1982) Previously known as Jubaea spectabilis.
Distinguishing features on the U of A campus: Pinnate leaves with narrow stiff leaflets folded to a pointed apex; very broad trunk; leaves yellowish-green. See in the Palm Garden (NW of the Education Bldg).
NANNORRHOPS - This is a monotypic genus native to the Middle East where it is wide-spread in the hills of the Arabian Peninsula, and from Iran to Pakistan. It is shrub-like, and grows in groves or stands. Adapted to harsh dry conditions, it is tolerant of lower temperatures than many palms. It is listed as USDA Zone 8.
1. Nannorrhops ritchiana - Origin: Middle East. Common name: Mazari Palm. Low growing clumping species, normally about 2-3 meters tall by 3 meters wide. Trunks are sub-terranean, but may emerge above ground with age. Leaves are very gray/blue, to 1.5 meters wide and long, and are wedged shaped. Segmentation is quite deep, divisions occur nearly to petiole. Segments further divide at tips. Petioles can have tiny teeth. The branched inflorescence is held erect. The flower stalk is terminal (once fruits mature, the stem dies off). Fruits are 1-1.5 cm round, dark orange, and somewhat sweet.
Distinguishing features on the U of A campus: One small individual planted on west side of Palm Garden (NW of Education Bldg) by PL S 235 class in 2009. A second one is south-west of Haury Anthropology.
PHOENIX - Better known as the Date Palm, the genus Phoenix includes about 17 species found extensively in Africa, Crete, Middle East, Asia, South-East Asia, the Philippines and Indonesia. These palms can be solitary or clumping, and small to large. The trunks are distinguishable by their rough texture and diamond-shaped scars. A unique feature of Phoenix is the induplicate venation of pinnate leaves only found in four other palm genera: Caryota, Arenga, Didymosperm, and Wallichia (McCurrach 1960). Towards the base of the leaf, the leaflets are reduced to long, stiff spines. Phoenix spp. are dioeciuos, and inflorescences protrude on a flattened stalk in an erect, broom-like arrangement.
1. Phoenix canariensis - Origin: Canary Islands Common Name: Canary Island Date Palm This palm grows to 20 meters tall and 70 cm diameter. Leaves are long pinnate (six meters), ascending, and deep green in color. The inflorescence is densely branched with creamy yellow flowers. The infructescence stalk is orange and distinctly flat, producing large clusters of golden to orange oblong fruits (2 cm long). (Blombery and Rodd 1982, Jones 1995).
Distinguishing features on the U of A campus: Upper trunk distinctly dark brown and apparently disintegrating; brightly colored orange fruits on flat stalked, branched infructescence; dark green leaf color with center leafs pointed upwards (ascending).
2. Phoenix dactylifera - Origin: Northern Africa Common Name: True Date Palm Young plants produce suckers which lead to a multi-stemmed habit unless trimmed. This palm grows to at least 20 meters tall and 30-40 cm in diameter. Leaves are ascending, gray-green in color, and six to seven meters long. These palms produce yellow (female) or cream (male) flowers and large oblong yellow or orange fruits (5 to 7 cm long). (Blombery and Rodd 1982, Jones 1995). This is the only Phoenix which bears commercial dates – a staple food for millions in Arabia, Persia, Egypt, and other nearby countries. (McCurrach 1960) The fruits of P. dactylifera are deep orange in color and have been used to cure bronchitis (La Barre 1959 in Balick, et al. 1990).
Distinguishing features on the U of A campus: Gray-green leaves; normally taller and more slender than P. canariensis; occasionally clustered at base; upper leaves ascending; whitish-yellow inflorescence surrounded by single woody bract.
3. Phoenix reclinata - Origin: Africa Common Name: Senegal Date Palm This species forms a large clump of many slender trunks curving away from each other and has numerous basal suckers. It normally grows to 15 meters and 10 to 12 cm in diameter. Crown more sparse with recurved bright green leaves. Slender, much-branched inflorescence subtended by boat-shaped bract which produces egg-shaped orangish-yellow fruits. Native to tropical Africa along margins of streams and soaks. (Jones 1995, Blombery and Rodd 1982).
Distinguishing features on the U of A campus: Leaves recurved and bright green in color; trunk more slender than other Phoenix; clustered habit.
4. Phoenix sylvestris - Origin: India Common Names: Silver Wild Date, Sugar Data Palm This palm grows about eight to twelve meters tall. Leaves are three to four meters long, and leaflets are bluish-green in color and tend to criss-cross. Its leaves tend to be descending more than ascending. A much branched inflorescence with yellow stalk produces purplish-red fruits. (Blombery and Rodd 1982) Its timber is used in construction, leaves used for thatch, baskets, bags, fans, and mats. Fibers from the leaf stalks are used to make paper and rope, and the leaf bases make pack saddles for oxen. Seeds and fruit from this palm are eaten and beverages and sugar are made from the vitamin-rich sweet sap. A juice made from the sap has even been bottled and sold as a soft drink in the cities of India (Dastur 1952 and Davis 1972 in Balick, et al. 1990).
Distinguishing features on the U of A campus: Leaves shorter than P. canariensis or P. dactylifera (3-4 meters as opposed to 6 meters); leaflets bluish-green and criss-cross; central leaves not, or barely, ascending; inflorescence bright yellow; fruits purplish-red. See a specimen located near southwest corner of Douglass Building.
5. Phoenix zeylanica - Origin: Sri Lanka Common Name: Ceylon Date Palm Slender palm with a solitary trunk to normally six meters tall and 20-30 cm in diameter, however the individual on campus approached 15 meters tall. Leaves pale green in color and trunk densely covered with old leaf bases. Several ranked leaflets which are stiff and sharply pointed. Oblong to obvoid fruit (12mm long) ripens from red to violet-blue. This species grow on seashores. (Blombery and Rodd 1982, McCurrach 1960).
Distinguishing features on the U of A campus: Leaflets several-ranked; short pale-green leaves (about 2 meters); curved, pendulous leaves; deep yellow-colored inflorescence. See one on the east side of Old Main.
RHAPIS - A genus that includes 12 species, mostly from the Far East. Clustering, dioecious (male and female plants are separate), with palmate leaves. Some species are quite hardy – to the teens. Many have been improved by growers, with some dwarf forms and some with variegated leaves.
1. Rhapis excelsa - Origin: China. Common name: Lady Finger Palm. A clumping palm with thin hairy stems up to 3 cm thick. Stems emerge along the perimeter of a clump. Circular fan-shaped leaves born on 7 cm petioles are shiny green above and below. Stiff leaf segments are of different widths and are bluntly truncated at their apices. Inflorescences are cream colored and grow from upper leaf axils.
Distinguishing features on the U of A campus: One large individual in the courtyard of the McClelland Building was a gift from Professor Emeritus Warren Jones. Two on the south side of the Main Library were planted in 2000.
SABAL - The genus Sabal includes about fifteen species which are found in the southeastern USA, northeastern Mexico, the Caribbean, Panama, and northern South America. Sabal exhibits a solitary habit with strongly costapalmate leaves, and the petioles of this group are unarmed. Leaf petiole bases are split, forming a distinct Y shape where the leaf bases join the trunk. These palms mostly grow in open habitats, including savanna, low hills, coastal dunes and swamps.
1. Sabal palmetto - Origin: North America, Bahamas, Cuba Common Names: Palmetto Palm, Cabbage Palm This species grows to 25 meters tall and about 35 cm diameter. Its leaves are costapalmate with a strongly arched costa, and threads hang from the between the leaf segments. Leaf segments are joined for about 1/3 of their length, and each of the segments are deeply divided. Inflorescence extends about as long the leaves, and comes to produce spherical black fruits 8-14 mm across. S. palmetto grows in variety of habitats – coastal dunes and tidal flats to seasonally flooded savannas, swamp and stream margins (Jones 1995).
Distinguishing features on the U of A campus: Costapalmate with strongly arched costa; split leaf bases; smooth petioles; on campus no taller than four meters.
2. Sabal mexicana - Origin: Texas and Mexico. Common name: Texas Palm, Texas Palmetto, Mexican Palm. Single stemmed palm to 15 meters tall. Heavy trunk to 90 cm in diameter, retaining leaf bases in a cross-hatch pattern. Leaves are deep blue green, curve downward with a strong midrib, and are up to a meter in length. Smooth thornless petioles can grow up to 1.5 meters. Both male and female flowers occur on same plant; branched inflorescences mature to dark showy fruits.
Distinguishing features on the U of A campus: Very handsome plants with arching leaves. A strong row can be seen on the north side of the Science Library.
3. Sabal minor - Origin: Southeastern US. Common name: Scrub Palmetto. A short palm with a subterranean trunk. Fan shaped leaves (to 1.5 meters in length) continue to emerge at soil level, so that final height is never more than the length of leaf plus petiole. Smooth petioles are a little longer than leaves. The midrib is short, resulting in an arch to the leaves. Branched inflorescences are erect, with cream colored flowers. Dark ripened fruits are 1-2 cm and hang heavy on the stalks.
Distinguishing features on the U of A campus: Three plants with very large leaves on the east side of Marvel Chemistry building.
4. Sabal uresana - Origin: Mexico Common Name: Sonoran Palmetto The trunk of this palm normally grows to about 20 meters tall and 30-40 cm in diameter. Large, rounded strongly costapalmate leaves crown the tree and are moderately to highly glaucous. Leaf segments of this species are joined for about 1/3 of their length. The crown is sparse and open relative to S. palmetto. Inflorescence are branched to three orders and extend about as long as leaves. The palm’s spherical or pear-shaped fruit measure 13-18 mm across and are brown-black in color. This species occurs in thorn and oak forest along water courses and valleys in Sonora and Chihuahua, Mexico. (Zona 1990, Jones 1995) In Mexico, timber from S. uresana has been used in construction and leaves for thatch (Schnabel 1964 in Balick, et al. 1990).
Distinguishing features on the U of A campus: Strongly arched costapalmate leaves; smooth petioles; leaves glaucous, bluish-green; very sparse, open crown. See an old tree on the west side of Chavez, reportedly planted by Forrest Shreve in the late 1930s.
SYAGRUS - Syagrus contains 32 species distributed from Venezuela to Argentina. Some species grow in rainforest, but most are found in drier open habitats like savanna and semi-arid scrublands. The palms are small to robust, and solitary to clustered. Leaves are pinnate.
1. Syagrus romanzoffianum - Origin: South America Common Names: Queen Palm, Giriba Palm The fairly slender, gray trunk of this species grows to about 15-20 meters tall and 20-35 cm in diameter. The trunk appears to be ringed at wide intervals. It is widely distributed in Brazil, Paraguay, Argentina, and Uruguay where it grows in forests and woodlands. The leaves are pinnate with leaflets spreading in different planes. The inflorescence is enclosed by a single long woody bract and are normally about 1.5 meters long. Flowers are cream-colored. Typically, S. romanzoffianum produces plump fruit about 2-2.5 cm long. (Jones 1995, Henderson, et al. 1995, McCurrach 1960) In Brazil the palm is often cut down to provide animal fodder in times of drought. Also, people eat the unexpanded leaves of apical buds and the fruit in some regions. Fallen fruits are fed to pigs, and palm trunks are often used in construction, frequently hollowed out to make water pipes or aqueducts for irrigation. (Blombery and Rodd 1982) Previously Arecastrum romanzoffiana.
Distinguishing features on the U of A campus: Pinnate leaves, leaflets several ranked with pendulous tips; tall grayish trunk to about 15 meters with conspicuous rings; long singular woody bracts subtends inflorescence.
TRACHYCARPUS - The genus consists of about nine species found in northern India, Burma, Nepal, northern Thailand and China. Habit varies from dwarf to medium-sized, and solitary or clumping. Leaves are palmate, and segments are shallowly bifid at the tips. The trunk exhibits a characteristic dense covering of coarse fibers. Trachycarpus include the most cold tolerant palms in the world. They are known to withstand temperatures as low as 0° F.
1. Trachycarpus fortunei - Origin: China Common Names: Chinese Windmill Palm, Chusan Palm This palm has a slender trunk covered with persistent but loosely arranged grayish-brown fibers and old leaf bases. It grows up to10-12 meters tall and displays dark green leaves with a glaucous, or grayish, under-surface. On the U of A campus these palms are about 2-6 meters in height. Small spines cover the petiole margins, and the leaf blades are unevenly divided more than half-way to the petiole. The palm is native to China where it grows in cold, mountainous regions. Small, yellow-colored unisexual flowers are arranged in a short densely-packed inflorescence sheathed with overlapping, whitish to brown bowl-shaped bracts. As the inflorescence matures its structure becomes more spread. The tree produces kidney-shaped bluish fruits (12 mm long). Fiber can be stripped from the trunk in pads and provides useful lining material for hanging baskets. In China, fibers are used to make fine waterproof cloaks, brooms, brushes and door mats (Jones 1995, Krempin 1993).
Distinguishing features on the U of A campus: characteristic fibrous bark; palmate leaves deeply divided and each leaflet shallowly bifid apex; on campus as tall as about six meters; spines on petioles inconspicuous but evident to touch.
WASHINGTONIA - The genus Washingtonia is made up of only two species and its native range stretches from the west coast of USA and Baja California to Sonora, Mexico. Washingtonia are tall, solitary palms with a costapalmate leaf divided to about half its length into segments. In both species, old dead leaves of this group form a characteristic persistent petticoat which hides the trunk and in the wild often extends to the ground. The inflorescence is long and arching beyond the leaves covered with many chaffy bracts. Coyotes eat fruits from this palm and play an active role in their dispersal (Uhl and Dransfield 1987). The palms grow in semi-arid, desert regions, usually forming colonies near water in gorges or canyons.
1. Washingtonia filifera - Origin: North America Common Names: American Cotton Palm, California Palm This palm is tall (to 20 meters) and fat with a heavy, barrel-shaped, gray trunk. The costapalmate leaves appear gray-green, and threads tend to hang from between leaf segments. Leaf petioles are armed with spines which progressively smaller towards the apex. The hastula is long and narrow, tapering to a point.W. filifera originates in the USA where it forms colonies in canyons of south-eastern California and western Arizona. (Baily 1936 in Balick, et al. 1990, Jones 1995) The Yuman Indians grind seeds from W. filifera into a meal for consumption. They also eat the fruit of this palm and use it in making beverages (Castettler and Bell 1951 in Balick, et al. 1990).
Distinguishing features on the U of A campus: Persistent petticoat of dead leaves (unless trimmed); costapalmate; long many-bracted, chaffy inflorescence; stout gray trunk – the broadest on campus; petiolar spines; thread fibers hang from leaves.
2. Washingtonia robusta - Origin: Mexico Common Names: Washington Palm, Skyduster, Mexican Fan Palm This palm grows taller than W. filifera (to 25 meters), and exhibits a much thinner trunk often flared at the base. Leaves are costapalmate and brighter green in color, and the petioles appear reddish-brown in color, especially when younger. The basal sheaths also appear reddish-brown. Cottony threads hang from the leaf, but disappear with age. A distinctive tawny white patch appears where the petiole meets the blade (surrounds the abaxial hastula). On young trees, reddish-brown spines line the petiole margins, but as the palm matures, spines become few and small or even disappear. Also, once the tree is mature, the leaflet tips become pendulous. The hastula of W. robusta is shorter than that of W. filifera and displays a more triangular shape (Baily 1936 in Balick, et al. 1990, Jones 1995).
Distinguishing features on the U of A campus: one of the tallest and skinniest trees on campus; bright green costapalmate leaves with a distinct white patch on the abaxial surface of the leaf where the petiole joins the blade; less frequently with persistent petticoat of dead leaves; conspicuous orangish spines on younger individuals; base of trunk often flared.
References
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