Trachycarpus H.Wendl., Bull. Soc. Bot. France 8: 429 (1861)

Primary tabs

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Number of Taxa

  • 9 species

Discussion

Biology And Ecology

  • Trachycarpus nanus and T. oreophilus have both been recorded from limestone hills; the latter has been found at altitudes up to 2400 m and appears not to be exclusive to limestone. Trachycarpus takil has been reported from damp oak forests at 2400 m altitude, where the ground is under snow from November to March. Trachycarpus fortunei, one of the most cold tolerant of all cultivated palms, is hardy in the British Isles. (J. Dransfield, N. Uhl, C. Asmussen, W.J. Baker, M. Harley and C. Lewis. 2008)

Common Name

Etymology

Diagnosis

Description

  • Dwarf or moderate, solitary or clustering, acaulescent or erect, unarmed or lightly armed, pleonanthic, dioecious or polygamous palms. Stem decumbent or erect, becoming bare and marked with conspicuous, rather close, oblique leaf scars, or clothed with persistent petiole bases and fibrous sheaths, or obscured by a skirt of dead leaves. Leaves induplicate, palmate, marcescent; sheath disintegrating into a mass of fine and coarse fibres, the upper margin ribbon-like, becoming twisted; petiole elongate, narrow, adaxially flattened or slightly rounded, abaxially rounded or angled, bearing scattered, deciduous indumentum or glabrous, armed along the margins with very fine teeth or unarmed; adaxial hastula well developed, rounded or triangular, abaxial hastula absent; blade fan-shaped to almost circular, equally or unequally divided along adaxial ribs into single-fold segments, shallowly bifid at the tips, longitudinally striate or not, the abaxial surface sometimes glaucous, sometimes dotted with minute brown scales, midrib conspicuous abaxially, transverse veinlets conspicuous or not. Inflorescences solitary, interfoliar, arching or ± erect, copiously branching to 4 orders; peduncle oval in cross-section, bearing sparse indumentum; prophyll complete, conspicuous, with a tubular base, and inflated distally, 2-keeled laterally, splitting apically and along one side, covered with deciduous indumentum; peduncular bracts 1–3, as the prophyll but single-keeled, rachis shorter or longer than the peduncle, bearing spirally arranged bracts similar to the peduncular bracts, but each subtending a first-order branch; bracts of subsequent orders inconspicuous, triangular, not sheathing; rachillae slender, stiff, short, very crowded, bright yellow to greenish, glabrous or sparsely hairy, bearing spirally arranged flowers, which are solitary or in clusters of 2–3, sessile or borne on low tubercles, each flower bearing a minute, apiculate, membranous bracteole. Flowers similar in both sexes; sepals 3, united at the base, triangular, short or long, glabrous; petals usually considerably exceeding the sepals, 3, distinct, imbricate, ovate, triangular-tipped or rounded, glabrous; stamens 6, filaments distinct, fleshy, ± parallel-sided, anthers short, oblong, sometimes slightly pointed, latrorse; staminodes when present, similar to fertile stamens but with flattened filaments and empty anthers, sometimes with filaments connate at the very base; carpels 3, distinct, follicular, hairy, ventral sutures partially open, stylar projections short, ovule basally attached, hemianatropous, surrounded dorsally and ventrally by a fleshy aril; pistillodes when present similar to, but much smaller than, the fertile carpels. Pollen ellipsoidal, with slight to obvious asymmetry; aperture a distal sulcus; ectexine tectate, finely rugulate-perforate, foveolate or reticulate, aperture margin slightly finer; infratectum columellate; longest axis 22–32 µm; post-meiotic tetrads usually tetrahedral, sometimes tetragonal or, rarely, rhomboidal [2/9]. Fruit usually developing from 1 carpel, purplish-black with a pale bloom, kidney-shaped to oblong, slightly grooved on the adaxial side with lateral or subapical stigmatic remains; epicarp thin, hairy in immature fruit, becoming glabrous in mature fruit, mesocarp thin with scattered layer of tannin cells, endocarp crustaceous. Seed kidney-shaped to oblong, endosperm homogeneous with a shallow to deep lateral intrusion of seed coat, sometimes also with very shallow ruminations; embryo lateral. Germination remote-tubular; eophyll simple, narrow, plicate. Cytology: 2n = 36. (J. Dransfield, N. Uhl, C. Asmussen, W.J. Baker, M. Harley and C. Lewis. 2008)

Anatomy

Relationships

  • Preliminary analyses indicate that Trachycarpus is monophyletic (Stührk 2006). The genus is sister to all other Rhapidinae except Chamaerops with low support (Baker et al. in review). Alternative placements include sister to Guihaia with moderate support (Asmussen et al. 2006) and sister to a clade of Rhapidophyllum, Guihaia and Rhapis (Uhl et al. 1995). (J. Dransfield, N. Uhl, C. Asmussen, W.J. Baker, M. Harley and C. Lewis. 2008)

Taxonomic accounts

Fossil record

  • Palmate leaves referred to Trachycarpus include: southern England, Lower Eocene (Bagshot Beds), T. raphifolia (Sternberg) Takhtajan (Chandler 1962); Russia, Caucasus, Middle Miocene (Takhtajan 1958; who considers that most specimens of fan palms from Russia should be referred to T. raphifolia), and Transcaucasia, Oligocene (Akhmetiev 1989); Czech Republic, Lower Miocene, T. rhapifolia (Czeczott and Juchniewicz 1975); northern India, upper Indus Valley, Miocene, T. ladakhensis (Lakhanpal et al. 1984). Chandler (1962) casts doubt on Takhtajan’s inclusion of Palaeothrinax mantelli (Reid and Chandler 1926) in Trachycarpus because, “the margins of the pinnules are thickened and there is no marked midrib.” A fruit containing a seed, from the Lower Eocene (London Clay) of southern England, is compared with Trachycarpus fruit (Chandler 1978). Some Monocolpopollenites pollen from the Tertiary of Hungary (Kedves and Bohony 1966) and monocolpate pollen from the Lower Miocene of Poland (Macko 1957) have been compared to Trachycarpus pollen but the pollen is of too general a coryphoid type to be conclusive. (J. Dransfield, N. Uhl, C. Asmussen, W.J. Baker, M. Harley and C. Lewis. 2008)

Uses

Bibliography

  • Dransfield, J. , Uhl, N. , Asmussen, C. , Baker, W.J. , Harley, M. & Lewis, C. 2008. Genera Palmarum. The evolution and classification of palms. Kew Publishing, Royal Botanic Gardens Kew.