Brahea Mart., Hist. Nat. Palm. 3: 243 (1838)

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Common Name

Uses

Description

  • Moderate, mostly solitary, rarely clustered, armed or unarmed, pleonanthic, hermaphroditic palms. Stem clothed with persistent leaf sheaths, in age becoming bare. Leaves induplicate, shortly costapalmate, marcescent; sheath becoming fibrous, persistent, eventually splitting basally; petiole short or long, concave, flattened, or channelled adaxially, rounded abaxially, margins unarmed or armed with sparse to dense, small or large teeth, sometimes floccose; adaxial hastula triangular to irregular, thin, membranous, at length fibrous, sometimes large, abaxial hastula a very low ridge or scarcely developed; blade nearly orbicular, regularly divided nearly to the middle or beyond into single-fold, stiff or flexible segments, deeply bifid at the apex, interfold filaments often present, surfaces glabrous, waxy or covered in caducous, floccose indumentum, midribs prominent, other veins fine, ± equal and close together giving a striate appearance, transverse veinlets inconspicuous, sometimes evident abaxially. Inflorescences solitary, interfoliar, nearly equalling or exceeding the leaves, erect or curving, branched to 4 orders; peduncle slender, short to medium; prophyll 2-keeled, closely sheathing, tubular, glabrous (?always), splitting irregularly abaxially; peduncular bracts 0–several, like the prophyll but single-keeled, glabrous or floccose; rachis much longer than peduncle; first-order branches distant, apparently lacking prophylls; subsequent bracts triangular, membranous, very inconspicuous; rachillae crowded, numerous, all branches and rachillae covered in a pale dense felt or deep pile of hairs. Flowers spirally arranged, solitary or in cincinni of 2–3, each subtended by a small bract, buds sometimes obscured by hairs until anthesis; sepals 3, distinct, imbricate, margins minutely toothed (?always); petals 3, united basally in a tube as long as the sepals, briefly imbricate, valvate apically, shallowly to deeply furrowed adaxially; stamens 6, borne at the mouth of the corolla tube, filaments connate into a 6-lobed ring, lobes triangular, abruptly narrowed at tips, anthers broadly elliptic to nearly oblong, dorsifixed, ± versatile, latrorse; carpels 3, follicular, united by the styles, ovule basal, erect, anatropous. Pollen ellipsoidal, slightly to extremely asymmetric; aperture a distal sulcus; ectexine tectate, finely perforate, perforate and micro-channelled, or perforate-rugulate, aperture margin slightly finer; infratectum columellate; longest axis 29–51 µm [4/10]. Fruit usually developing from 1 carpel, globose or ovoid, dark blue to black at maturity, abortive carpels basal, stigmatic remains apical; epicarp smooth, mesocarp fleshy, endocarp crustaceous. Seed basally or subbasally attached, globose or ellipsoidal, endosperm homogeneous, very shallowly to deeply penetrated by a smooth intrusion of seed coat; embryo subbasal to lateral. Germination remote-ligular; eophyll entire. 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 study of the Middle Eocene Princeton chert of British Columbia, Canada shows palm vegetative organs to be the most common elements: five stems up to 9 cm wide with attached petiole bases and roots, plus numerous additional isolated petioles, midribs and laminae. According to Erwin and Stockey (1991) comparison with extant palms suggests that fossil stem and leaf anatomy is most similar to two coryphoid genera, Rhapidophyllum and Brahea. A hermaphroditic flower, Palaeoraphe dominica (Poinar 2002b) described from the Eocene Dominican amber is compared with flowers of Brahea, Acoelorrhaphe and Colpothrinax, although the flower is considered to resemble Brahea most closely, Poinar (2002b) describes differences in the style, stigma, ovary and stamens that separate the fossil flower from those of Brahea. The age of the amber is estimated to be somewhere between mid Eocene and mid Miocene. Brahea-like pollen (Graham 1976) is described from the Upper Miocene of Mexico (Paraje Solo flora, Veracruz). Small monosulcate grains, Palmaemargosulcites fossperforatus, from palm flower compression fossils, recovered from the Middle Eocene oil shales of Messel, Germany are compared with pollen of a number of coryphoid genera, including Brahea (Harley 1997). (J. Dransfield & N. Uhl & C. Asmussen & W.J. Baker & M. Harley & C. Lewis, Genera Palmarum. The evolution and classification of palms. 2008)A

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