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Poaceae: Sporobolus durus

Sporobolus durus Brongn.

Sporobolus durus Brongn.

Species

Sporobolus durus Brongn.

Original Distribution

Acsention Island

Extinction Data

IUCN = Extinct

Description

Annuals or perennials, tufted or sometimes with creeping rhizomes or stolons. Leaf blades flat or rolled, linear to narrowly lanceolate; ligule a line of hairs. Inflorescence an open or contracted panicle, rarely spikelike. Spikelets with 1 floret, subterete, not compressed or keeled, glabrous; rachilla disarticulating above glumes; glumes usually shorter than lemma, unequal, membranous, deciduous or persistent, 1-veined or veinless, apex obtuse, acute or acuminate; lemma elliptic to narrowly ovate, thinly membranous, 1-3-veined, glabrous, rounded on back, awnless; palea equaling or shorter than lemma, depressed between veins and often splitting lengthways as grain grows. Stamens 2-3. Grain globose to ellipsoid, rounded or truncate, pericarp free, commonly swelling when wet and expelling the grain, which often adheres to spikelet apex

Number of Specimens at Kew

5

Kew Herbcat Barcode Number

K000367559,K000367560,K000367558,K000212934,K000212935

Other Information

The last assessment (Cronk 1980) listed this species as Endangered. New information indicates that the species can reasonably be considered as extinct as repeated surveys have failed to locate any plants. Last confirmed sighting remains 1886. No trace of this species was found after extensive searches of White Horse Hill in 1998, where it was last recorded in 1886 at 460 m (Cronk 1980). The introduced grass Melinis minutiflora P.Beauv. is now the dominant grass in this area and it is unlikely that S. durus could compete with this vigorous species. If any surviving specimens persist, they are likely to be in areas inaccessible to survey, for example, small ledges on cliff faces. Due to the inability to locate this species in the wild, S. durus should now be regarded as extinct. The introduction of species such as M. minutiflora are likely to be responsible for the reduction in the distribution of S. durus (Cronk 1980). This species was first recorded by the France collector and D’Urville in XXX and was described in 1829 by Brongniart. This endemic grass grew in tussocks up to 30 cm high. The last recorded specimen was found in 1886 at 460 m altitude on the west side of Weather Post. The species also used to occur on Green Mountain. Plants of this genus have never been an important part of the lowland flora on the island. It has not been seen since despite an extensive search for it. Cause: Competition, flora (the introduced grasses Melinis minutiflora and Sporobolus africanus are now dominant in this area and may have entirely displaced it.) and the introduced goats and sheep have probably also played an important role in its extinction.

Information Sources

Ashmole, P. and Ashmole M. 2000. St Helena and Ascension Island: a natural history. Anthony Nelson, Oswestry, UK. Chen Shouliang, Jin Yuexing, Zhuang Tide, Fang Wenzhe, Sheng Guoying, Liu Liang, Wu Zhenlan, Lu Shenglian, Sun Bisin, Hu Zhihao, Wang Song, Sun Xiangzhong, Wang Huiqin, Yang Xilin, Wang Chaopin, Li Binggui & Wen Shaobin. 1990. Gramineae (Poaceae) (4). In: Chen Shouliang, ed., Fl. Reipubl. Popularis Sin. 10(1):1401; Chen Shouliang, Zhuang Tide, Fang Wenzhe, Sheng Guoying, Jin Yuexing, Liu Liang, Sun Bisin, Hu Zhihao & Wang Song. 1997. Gramineae (Poaceae) (5). In: Chen Shouliang, ed., Fl. Reipubl. Popularis Sin. 10(2): 1301; Cronk, Q.C.B. 1980. Extinction and survival in the endemic flora of Ascension Island. Biological Conservation. 17: 207-219.