Sciaphila

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Sciaphila

Description

Small and delicate, echlorophyllose, mostly erect, simple or branched herbs up to c. 45 cm high (in Mal.). Monoecious; Leaves scale-like, scattered, spaced, sessile, mostly appressed, sometimes amplexicaul. Inflorescences terminal, racemose, all around or most flowers to one side, with male and female flowers, or male and bisexual flowers, or only bisexual flowers. Flowers actinomorphic, perianth with 4-10, usually 6, valvate, patent or reflexed, equal or alternatingly unequal (larger and smaller) segments, connate at base, at the top glabrous or bearded by uniseriate hairs, or with knob-like appendages. Fruits obovoid, 3-8 times as large as the ovaries, with persistent, partly shrivelled style, dehiscent lengthwise from the apex, first abaxially, later also adaxially. Seed 1, endospermous, elliptic to ovate, the surface netted and mostly lined, sometimes with a dent.

Distribution

Africa:, Ivory Coast (Ivory Coast present); Nigeria (Nigeria present) Africa only in the West: present Asia-Temperate:, Hainan (Hainan present) Asia-Tropical:, Assam (Assam present) Australasia:, Queensland (Queensland present) Bellenden Ker Ra., c. 16° S: present Botel Tobago Is: present Cameroun: present Central Pacific: absent Melanesia: present Micronesia: present N. Thailand: present Southern Japan: present Western Polynesia: present continental Southeast Asia: present pantropical and subtropical: present
About 33 spp.; pantropical and subtropical in Southern Japan and Bonin Is., in Africa only in the West (Ivory Coast, Nigeria, Cameroun), in continental Southeast Asia only in Assam and N. Thailand, in Hainan and Botel Tobago Is., throughout Malesia (14 spp.), not in the Central Pacific, but rather well represented in Micronesia and Melanesia, and Western Polynesia; in Australia only locally in Queensland (Bellenden Ker Ra., c. 16° S). .

Morphology

Several large papers have been devoted to the morphology and anatomy, notably by JOHOW (1889), POULSEN (mainly on the embryology) (1906), WIRZ (1910), and TOMLINSON (1982).

The anatomy is reduced and stomata are absent. Whether the plants are annual or perennial is not clear; probably they are annual.

The pollen is that of a Monocot, the grains being inaperturate, as in Scheuchzeria, monosulcate in Sciaphila, and trinucleate as in most Alismatiflorae.

The ovule is orthotropous first, anatropous later. The single integument is two cell layers thick. The seed, c. 1 mm in size, lacks endosperm and the cells of the testa are filled with air, which might favour wind dispersal, anyway at very short distances only, with respect to its 'concealed' habit and small size of the plants.

Taxonomy

Following SCHLECHTER (1912), GIESEN ( 1938) distinguished between Sciaphila Bl. and Andruris SCHLTR, on account of the absence cq. presence of what he called an awl-shaped prolonged connective. Actually the anther is dorsally attached near the base of the usually very long filament. The apical part of the latter is easily shed, as GIESEN himself already noted, and hence the structure is often difficult to recognize.

Using this feature as a character on generic level would in my opinion lead to artificial distinctions. This becomes clearly evident in comparing the type specimens and/or descriptions for example of Sciaphila arfakiana and Andruris anisophylla, and of S. tuberculata and A. clemensiae, which are all otherwise identical; in fact they represent only a single species, Sciaphila arfakiana.

GIESEN had subdivided the genus into a number of sections and subsections which can be retained. The species accepted for Malesia are accommodated in the key almost all according to his subdivision.

Cytology

Chromosome numbers are few and only known from Sciaphila. OHBA& SINOTO found for the non-Malesian S. japonica 2n = 48; LARSEN for S. thaidanica from N. Thailand 2n = 28; GREEN & SOL-BRIG for the New Caledonian S. dolichostyla 2n = 44, while SOLBRIG noted for S. densiflora (in sched. P.S. GREEN 1329) the number as 2n = 22.

Notes

As essential characters for specific distinction are mainly found in the structure of the androecium, collectors should gather ample material and ensure that male flowers are represented, and check whether plants with bisexual flowers are extant. Hitherto these are only found in S. maculata and S. tenella. The structure of the stamens can be best observed in mature buds or very young flowers.

The great influx of material since GIESEN'S monograph has led to a rather heavy reduction in the number of accepted species in Malesia and adjacent countries. GIESEN recognized for Malesia 49 spp. and 2 doubtful ones; one, S. buruensis being added later. In the present revision I recognize 14 spp., plus a doubtful one.

In the 'Identification Lists of Malesian Specimens' n. 63, published simultaneously with this revision, all names in Sciaphila of Malesia and adjacent regions in the West Pacific are listed, with indication of their types and disposition.

Citation

MEERENDONK - in Ident. Lists Males. Specim. 1983
SCHLTR - in Bot. Jahrb. 1912: 3 fig.
GIESEN - in Pfl. R. Heft. 1938: 30
GIESEN - in Pfl. R. Heft. 1938: 15
BECCARI - in Malesia. 1890: 329