Borassus L., Sp. Pl. : 1187 (1753)

Primary tabs

http://media.e-taxonomy.eu/palmae/photos/palm_tc_346107_4.jpg

Distribution

Map uses TDWG level 3 distributions (http://www.nhm.ac.uk/hosted_sites/tdwg/geogrphy.html)

Bangladesh (World Checklist of Arecaceae )B Benin (World Checklist of Arecaceae )B Burkina (World Checklist of Arecaceae )B Cambodia (World Checklist of Arecaceae )B Cameroon (World Checklist of Arecaceae )B Central African Republic (World Checklist of Arecaceae )B Chad (World Checklist of Arecaceae )B China South-Central (World Checklist of Arecaceae )B Comoros (World Checklist of Arecaceae )B Ethiopia (World Checklist of Arecaceae )B Ghana (World Checklist of Arecaceae )B Guinea-Bissau (World Checklist of Arecaceae )B India (World Checklist of Arecaceae )B Ivory Coast (World Checklist of Arecaceae )B Jawa (World Checklist of Arecaceae )B Kenya (World Checklist of Arecaceae )B Laos (World Checklist of Arecaceae )B Lesser Sunda Is. (World Checklist of Arecaceae )B Madagascar (World Checklist of Arecaceae )B Malawi (World Checklist of Arecaceae )B Malaya (World Checklist of Arecaceae )B Mali (World Checklist of Arecaceae )B Mozambique (World Checklist of Arecaceae )B Myanmar (World Checklist of Arecaceae )B New Guinea (World Checklist of Arecaceae )B Niger (World Checklist of Arecaceae )B Nigeria (World Checklist of Arecaceae )B Northern Provinces (World Checklist of Arecaceae )B Senegal (World Checklist of Arecaceae )B Socotra (World Checklist of Arecaceae )B Sri Lanka (World Checklist of Arecaceae )B Sudan (World Checklist of Arecaceae )B Sulawesi (World Checklist of Arecaceae )B Tanzania (World Checklist of Arecaceae )B Thailand (World Checklist of Arecaceae )B Togo (World Checklist of Arecaceae )B Uganda (World Checklist of Arecaceae )B Vietnam (World Checklist of Arecaceae )B Zaire (World Checklist of Arecaceae )B Zambia (World Checklist of Arecaceae )B Zimbabwe (World Checklist of Arecaceae )B
Six species have been recognised. They occur in Africa, Madagascar, north-eastern Arabia, through India and Southeast Asia to New Guinea and Australia. Borassus is one of the most widespread palm genera. (J. Dransfield & N. Uhl & C. Asmussen & W.J. Baker & M. Harley & C. Lewis, Genera Palmarum. The evolution and classification of palms. 2008)A

Discussion

Diagnosis

Biology And Ecology

Etymology

Uses

Description

  • Tall, robust, solitary, armed, pleonanthic, dioecious, tree palms. Stem massive, covered in a lattice of leaf bases abscising cleanly in older specimens, then rough, ringed with wide leaf scars. Leaves induplicate, strongly costapalmate; sheath open early in development, later with a wide triangular cleft at the base of the petiole; petiole deeply channelled adaxially, rounded abaxially, surfaces smooth to minutely rough, margins of sheath and petiole armed with coarse irregular teeth; adaxial hastula conspicuous, triangular or scalloped, abaxial hastula a low ridge (?always); blade suborbicular to flabellate, divided along adaxial folds to ca. 1/2 its length into regular, stiff single-fold segments, these shortly bifid, interfold filaments present or absent, surfaces smooth, ramenta or tomentum along abaxial costa and ridges of folds, midribs prominent abaxially, transverse veinlets conspicuous, short, numerous. Inflorescences interfoliar, shorter than the leaves, the staminate and pistillate dissimilar. Staminate inflorescence branched to 2 orders; peduncle very short; prophyll 2-keeled, with long tubular base, limb short, pointed, variously split apically; (?)peduncular bracts lacking; rachis also short, rachis bracts similar to the prophyll; first-order branches long, flattened, each bearing a prophyll and branched digitately into several (1–3) rachillae; rachillae large, catkin-like, elongate, bearing spirally arranged, imbricate bracts, connate laterally and distally to form large pits, each containing a reflexed cincinnus of ca. 30 staminate flowers, exserted singly in succession from the pit mouth. Staminate flowers each subtended by a long membranous bracteole; sepals 3, asymmetrical, connate only basally or to 2/3 their length, distinct lobes keeled, elongate, membranous, stiff; corolla with a long stalk-like base and 3 short, rounded lobes, ridged adaxially; stamens 6, filaments short, triangular, anthers medifixed, elongate, latrorse; pistillode small, conical. Pollen ellipsoidal, bi-symmetric; aperture a distal sulcus; ectexine tectate, reticulate or finely perforate-rugulate, rarely foveolate-reticulate, with psilate supratectal gemmae, aperture margin similar but often without supratectal gemmae; infratectum columellate; longest axis 42–85 µm [2/6]. Pistillate inflorescence unbranched or with a single first-order branch; peduncle short; prophyll tubular, pointed, 2-keeled, split ventrally about 1/2 its length; peduncular bracts few (2 or more), if present as long as or longer than the peduncle; rachilla massive, bearing large cupular bracts, the first few empty, the subsequent each subtending a single pistillate flower, several empty bracts above the flowers. Pistillate flowers large, each bearing 2 lateral cup-like, rounded, leathery, bracteoles; sepals 3 distinct, imbricate, thick, rounded; petals 3, similar to sepals; staminodes triangular, connate basally in a low cupule, sterile anthers present or not; gynoecium rounded, tricarpellate, with a central, basal septal nectary, stylar region hemispherical, stigma a low knob, carpels each with a basal, orthotropous ovule, and 2 lateral bodies, perhaps vestigial ovules. Fruit large, rounded, sometimes wider than long, bearing 1–3 seeds, stigmatic remains apical, perianth enlarged, persistent; epicarp smooth, mesocarp thick, fibrous, often fragrant, endocarp comprising 3 hard bony pyrenes. Seed shallowly to deeply bilobed, pointed, basally attached, endosperm homogeneous with a central hollow; embryo apical. Germination remote-tubular; eophyll undivided, elliptical. Cytology: 2n = 36. (J. Dransfield & N. Uhl & C. Asmussen & W.J. Baker & M. Harley & C. Lewis, Genera Palmarum. The evolution and classification of palms. 2008)A

Fossil record

  • A well-preserved leaf impression, Amesoneuron borassoides, from the Indian Deccan Intertrappean of Madhya Pradesh (although the age span of these volcanic deposits is controversial, see Chapter 5) is described by Bonde (1986a) and compared, particularly, with Borassus. An Upper Cretaceous (Senonian) seed was compared with Borassus (Monteillet and Lappartient 1981), but this comparison has proved to be incorrect (Uhl and Dransfield 1987; Bayton 2005). Fossil stem, Palmoxylon aschersonii, from Paleogene and Neogene of Algeria and Lower Miocene of Libya is compared with Borassus aethiopum (Louvet and Magnier 1971; Boureau 1947; Boureau et al. 1983), but this is considered a doubtful comparison (Bayton 2005). From the Indian Miocene, petrified stems, Palmoxylon coronatum, are also compared with Borassus (Mahabalé 1959, Sahni 1964, Roy and Ghosh 1980). Fossil palm roots from the Deccan Intertrappean of Nahwargaon, Maharashtra (Ambwani 1981) is compared with B. flabellifer. (Comparisons of palm stem wood or root to generic level should always be viewed with caution). A seed, Upper Senonian (Monteillet and Lapartient 1981), seems very questionable. (J. Dransfield & N. Uhl & C. Asmussen & W.J. Baker & M. Harley & C. Lewis, Genera Palmarum. The evolution and classification of palms. 2008)A

Relationships