Schoenus
Content
Description
Perennials with woody, abbreviated or shortly creeping rhizome, more rarely annuals.
Leaves either all basal, or basal and cauline, linear, often setaceous, canaliculate, sometimes reduced to mucronate sheaths;
Inflorescence terminal, racemose or paniculate, consisting of some distant fascicles of branches subtended by a leafy bract, or contracted and head-like.
Flowers in the hollows of the zigzag rachilla, usually bisexual, but the uppermost often more or less reduced (male or functionally male).
Stamens (1-)3(-6), (in Mal. (2-)3);
Distribution
Almost cosmopolitan present, Asia-Tropical: New Guinea present, Australasia, Europe present, Micronesia present, New Caledonia present, New Zealand present, SE. Asia present, continental Australia present, tropical South America present
About 80 spp., mainly distributed over SE. Asia and Australia; some spp. extend eastward to New Zealand, New Caledonia, and Micronesia, a few others westward to Europe; a few spp. occur in extratropical South America; S. ferrugineus L. is almost cosmopolitan. The centre of development of the genus is to be found in continental Australia (more than 60 spp.). In Malesia 13 spp., 11 of which occur in New Guinea.
Notes
The 9 species LINNAEUS originally assigned to Schoenus have in the course of time all been transferred to other genera by VAHL, BROWN, LINK, NEES, and KUNTH. AS more recent authors only two of them (S. nigricans L. and S. ferrugineus L.) recognized as true Schoenus spp., it seems advisable to accept S. nigricans L. as the type species of the genus.
R. BROWN restricted Schoenus to those species in which the perianth is absent, and created the genus Chaetospora for the species in which the perianth is represented by hypogynous bristles. BENTHAM pointed out that often in the same species the bristles may be present or absent, and consequently he referred all Chaetospora spp. to Schoenus. His circumscription of the latter genus was accepted by nearly all subsequent authors.
Schoenus as circumscribed by BENTHAM and CLARKE is undoubtedly a rather homogeneous group, mainly characterized by the peculiar structure of the rachilla (lower internodes very short, upper ones elongated and zigzag).
It is easily discernible from the other Cyperaceous genera in Malesia with exactly distichous arrangement of the glumes as follows:
Specific delimitation is extremely difficult throughout the genus. BENTHAM’S remark that further study from the living plants or from specimens gathered in all the different stages of development of the flowers is required, is in force up till the present day.
R. BROWN restricted Schoenus to those species in which the perianth is absent, and created the genus Chaetospora for the species in which the perianth is represented by hypogynous bristles. BENTHAM pointed out that often in the same species the bristles may be present or absent, and consequently he referred all Chaetospora spp. to Schoenus. His circumscription of the latter genus was accepted by nearly all subsequent authors.
Schoenus as circumscribed by BENTHAM and CLARKE is undoubtedly a rather homogeneous group, mainly characterized by the peculiar structure of the rachilla (lower internodes very short, upper ones elongated and zigzag).
It is easily discernible from the other Cyperaceous genera in Malesia with exactly distichous arrangement of the glumes as follows:
- (a) Hypogynous bristles are always absent in Cyperus and Fimbristylis, but often present in Schoenus.
- (b) Long-plumose bristles are characteristic of Malesian Carpha and Costularia spp., but in Malesian Schoenus spp. only found in S. nitens.
Specific delimitation is extremely difficult throughout the genus. BENTHAM’S remark that further study from the living plants or from specimens gathered in all the different stages of development of the flowers is required, is in force up till the present day.
Citation
LINNE 1883 – In: B. & H., Gen. Pl. 3: 1062
LINNE 1938 – In: Fedde, Rep. 44: 161
Benth. 1878 – In: Fl. Austr.: 352
non BENTH. 1883 – In: B. & H., Gen. Pl. 3: 1063
BOECK. 1874 – In: Linnaea: 273
LINNE 1754: Gen. Pl, ed. 5: 26
KÜK. 1938 – In: Fedde, Rep. 44: 5
Miq. 1856 – In: Fl. Ind. Bat.: 339
Clarke 1908 – In: Kew Bull.: 12
LINNE 1940 – In: Fedde, Rep. 48: 246
BOECK. 1874 – In: Linnaea: 287