All Floras      Advanced Search
Login | eFloras Home | Help
Taiwan Gramineae | Family List | Poaceae

Ischaemum L., Sp. Pl. 2: 1049. 1753.

鴨嘴草屬

Ischaemum indicum
leaf cs section 2

Credit: cs kuoh

Annuals or perennials; culms solid. Leaf-blades lanceolate or linear, sometimes with a pseudo-petiole. Inflorescence composed of 2 to several spike-like racemes, more or less digitately arranged, if only 2 racemes present, then usually very closely appressed, at first sight appearing as a single racme. Spikelets dorsally compressed, 2-flowered, sometimes 1-flowered, in alternate pairs, the one sessile: and the other pedicelled. Pedicelled spikelet falling entire from pedicel, the callus blunt, or usually stipe-like and bearded. All sessile spikelets are placed in front, all pedicelled spikelets behind, sometimes pedicels very short; lower glume oblong or lanceolate, convex, often hardened in lower half, often tuberculate or transversely rugose, often winged towards apex; entire or a 2-lobed, numerous-nerved, the nerves of the hardened lower glume only distinct near top, the margins inrolled or inflexed; upper glume narrower, often longer, boat-shaped, often keeled, acute, muticous or with very short awn; lower lemma shorter than lower glume, ovate-oblong, apex narrowed, thinly membranous; lower palea nearly as long, oblong; stamens 3, or reduced into staminodes; upper lemma well-developed, convex, hyaline, entire or 2-fid and awned from sinus, the awn short or long, the nerves 3-5 upper palea 2-nerved; stamens 3; styles 2, free, the stigmas plumose. Caryopsis oblong.

About 50 species distributed in the tropical and subtropical regions; nine species.

One variety and two forms are found on the plains and littoral regions of Taiwan.


KEY TO THE SPECIES and VARIETIES

1 Lower glume of sessile spikelets transversely rugose.   (2)
+ Lower glume of sessile spikelet not transversely rugose.   (4)
       
2 (1) Lower glume with 2-4 discontinuous ridges; pedicels and rachis-joints not thickened   var. gibbum
+ Lower glume with 4-5 continuous ridges; pedicels and rachis-joints thickened   (3)
       
3 (2) Spikelets about 5.5 mm long; plant body 60-70 cm high   var. segetum
+ Spikelets about 4 mm long; plant body up to 30 cm high   Ischaemum akonense
       
4 (1) Sessile spikelets up to 5 mm long, obovate to oblong; pedicelled spikelets with geniculate awn; culms creeping   Ischaemum indicum
+ Sessile spikelets 6-9 mm long, lanceolate; pedicelled spikelets awnless or with a straight awn. 6. Racemes not exceeding the uppermost sheath; leaves petiolate   (5)
       
5 (4) Racemes not exceeding the uppermost sheath; leaves petiolate   Ischaemum muticum
+ Racemes far exceeding the uppermost sheath; leaves not petiolate.   (6)
       
6 (5) Lower glume of sessile spikelets flattened and nerved at upper part , coriaceous below middle; if awned, column of awn not exceeding the spikelet.   (7)
+ Lower glume of sessile spikelets, flat, slightly coriaceous at base; internode of rachis yellow, villous; column of awn far exceeding spikelet   (9)
       
7 (6) Sessile spikelets bearing a geniculate awn; lower glume lanceolate, narrowly winged   Ischaemum crassipes
+ Sessile spikelets awnless or straight awned; lower glume broadly elliptic, broadly winged.   (8)
       
8 (7) Lower glume of sessile spikelet, peduncle and sheaths not villous   Ischaemum crassipes
+ Lower glume of sessile spikelet pilose; peduncle and sheaths villous   Ischaemum aristatum
       
9 (6) Lower glume of sessile spikelets keeled but wingless, narrow; ligule truncate   var. aristatum
+ Lower glume of sessile spikelets keeled and winged, broadly lanceolate; ligule tongue-like   Ischaemum setaceum

  • List of lower taxa


     

    Related Objects  

    Flora of China  
  • Ischaemum.pdf
  • PDF

  •  |  eFlora Home |  People Search  |  Help  |  ActKey  |  Hu Cards  |  Glossary  |