Ancistrocladus hamatus
- =Ancistrocladus vahlii in Nova Acta Phys.-Med. Acad. Caes. Leop.-Carol. Nat. Cur. 18: 325. 1836, nom. illeg., syn. sec. Taylor & al. 20052
Notes
Like Harriman (1987), we have seen no collections of this species with flowers adequately preserved for study. The floral morphology of this species is thus still known primarily from the detailed description and figures of Thwaites (1849), which were based apparently on living plants, and Har-riman's notes. This species appears from Harri-man's figure to have a well-developed disk that surrounds the bases of the three styles, and the typically capitate stigmas appear to be missing from the short linear styles in his figure and his description. Thwaites seems to have considered the receptacular disk to be the style, and the three free linear styles to be the stigmas. Thwaites concentrated most of his descriptive efforts (1849: figs. 6-16) on the ovules, seeds, and embryos, and noted with regard to the general habit of Ancistrocladus hamatus that the plant "is very abundant in some of the warmer districts of Ceylon, and owing to its spreading so much by its roots, is a very troublesome weed to the cultivator." Harriman (1987: 2) gave the ele-vational range of A. hamatus as extending up to 2000 m, but the source of his data is not given. Ramamoorthy (1976) and Harriman (1987) have suggested that Ancistrocladus hamatus is synonymous with A. heyneanus of continental India. However, these species are clearly distinguished by their stamen number, 5 in A. hamatus versus 10 in A. heyneanus, and by their fruits, with the nut portion larger (20 X 15-19 mm) in A. hamatus and smaller (ca. 5X5 mm) in A. heyneanus. The type collection of Wormia hamata comprises a number of duplicates that vary markedly in morphology. This collection appears to include samples of the various growth stages of these plants, with these various stages later distributed unevenly among institutions. The isotype at A and one of the isotypes at BM lack hooks and have relatively long narrow leaves that appear to have come from a juvenile plant. Another of the isotypes at BM, one at P, the holotype and isotypes at C, and the isotype at L have fertile hook-bearing branchlets with fruits. The other isotype at P has only one detached leaf, of the form found on the hook-bearing branch-lets. The specimens distributed under the type number of Bigamea thwaitesii (Thwaites 1600: BM 012417!, BM 012418!, BR [2]!, GH!, HAKS!, L!, P [3]!, SING!, US [2]!) represent a more uniform set. These specimens each have a fertile, hook-bearing branchlet with fruits, except the lectotype at BM has both a hook-bearing branchlet and a robust, perhaps juvenile stem with markedly larger leaves. Tieghem (1903) treated the Ancistrocladus plants of Sri Lanka as a distinct endemic genus, Bigamea, based on their 5 rather than 10 stamens, and regarded Bigamea as comprising two species, the previously described B. hamata and his new species B. thwaitesii. Tieghem (1903) actually used two different names in this article for his new species, A. thwaitesii (p. 154) and B. thwaitesii (p. 155), but he did state clearly that B. thwaitesii was the name he accepted, thus this name must be considered the one that is validly published. Tieghem separated his two Sri Lankan species based on leaf dimensions, 20 X 4 cm in B. thwaitesii versus 8 X 2.5 cm in B. hamata, and also by the leaf blades being less coriaceous with flat margins in B. thwaitesii versus coriaceous with revolute margins in B. hamata. However, Thwaites regarded the Sri Lankan plants as all belonging to one species, so his specimens were all distributed under the same number. No specimens have been found that were annotated as B. thwaitesii by Tieghem, and his nomenclatural work does not always conform to modern standards so interpretation of his intent is sometimes difficult. Of the 13 duplicates of Thwaites C.P. 1600 that were studied, only BM 012417 matches Tieghem's description of Bigamea thwaitesii. Thus we have selected this specimen as the lectotype and we exclude the remaining duplicates listed above from this typification; another duplicate reported to be at K has not been seen.
Description
Juvenile plants unknown. Juvenile leaves unknown. Adult stems climbing with height not noted, to 1 cm diam. [probably becoming larger but no data], with bark purplish brown, smooth to roughened, bearing some scattered leaves and also lateral branchlets to 30 cm long, these each bearing 1 to several hooks and sometimes a terminal rosette of leaves; hooks recurved to spiraling, 11-17 mm diam. Adult leaves drying papyraceous to chartaceous, on both surfaces shiny, in life not seen, drying discolorous, dark brown above, paler brown or yellow-brown below; pits dimorphic, small pits frequent on both surfaces though usually denser on adaxial surface, large pits 0.4-0.5 mm diam., circular, occasional on adaxial surface; midrib adax-ially shallowly sulcate, abaxially prominent, terminating in a tiny gland; secondary veins prominulous on both surfaces; tertiary veins reticulated and prominulous on both surfaces; margins plane to narrowly revolute; stem leaves with persis-tence unknown, elliptic to oblong or oblanceolate, sometimes falcate, 7.1-29.3 X 2.1-7.3 cm, L/W 3.4-5.6, at apex acute to rounded, at base cuneate to acute; secondary veins 10 to 18 pairs; leaves at branchlet apices with persistence unknown, elliptic, (8.0-)14.5-33.1 X (2.9-)4.6-8.5 cm, L/W 3.2-6.0, at apex acute to rounded and sometimes abruptly shortly acuminate, at base narrowly cuneate to long-attenuate; secondary veins 15 to 19 pairs, with intramarginal vein situated 1-2 mm from margin. Inflorescence lax, paniculate, lateral among leaves at apices of branchlets, occasionally bearing hooks, without bracteal leaves; peduncle 1.2-2.2 cm long, often flexuous; branched portion corymbiform, 7.0- 8.5 X 4.5-5.0 cm, dichotomously branched; bracts triangular, 0.7 X 0.4-0.6 mm, at apex acute, at base obtuse, marginally entire to erose at apex, abaxially eglandular; pedicels ca. 2.0 mm long. Flowers all shortly pedicellate [not seen; this description from Thwaites, 1849]; sepals 5, elliptic to elliptic-oblong, rounded and entire at apex, at base cuneate to obtuse and decurrent on ovary, color unknown, apparently eglandular abaxially, unequal with apparently 3 larger sepals and 2 smaller sepals; petals 5, imbricate, elliptic to suborbicular, color unknown, about equal to longest sepal and longer than other sepals; stamens 5, alternate with petals; filaments stout, pyramidal, equal, length unknown; anthers with size unknown; ovary fully in-ferior, ca. 1 mm long; styles 3, size unknown, stigmas not seen. Fruit turbinate; nut 20 X 15-19 mm, on sides longitudinally shallowly 5-ridged by decurrent margins of accrescent sepals; persistent sepal limbs spreading, chartaceous to papyraceous, unequal, the 3 larger spathulate, 22-40 X 9-14 mm, the 2 smaller narrowly oblong to spathulate, 8-20 X 5-10 mm; pericarp drying rust brown, coriaceous; seed not seen.