Chase — Notes on Genera of Panicece. IV. 151 



to be commonly separately deciduous, as stated by Hooker, the pair of 

 florets joined together, being found persistent in mature panicles after 

 one or both glumes bave fallen. A number of specimens show persistent 

 glumes from which the florets have fallen, but these are much fewer than 

 the persistent florets from which the glumes have fallen. Several panicles 

 have been found in which both of these occur, but in the great majority 

 of cases the spikelets are either present entire, or wholly fallen — though 

 the parts may have fallen separately. The second floret articulate on the 

 rachilla, falling separately, appears from the examination of our speci- 

 mens to occur only very rarely, and then only when the lower floret is 

 staminate, or at least not perfecting a grain. It may here be noted that 

 in Panicum capillare and its close allies the fruit frequently falls from the 

 temporarily persistent glumes and sterile lemma, and that occasionally in 

 P. diehotomum and its allies the glumes and sterile lemma fall, leaving 

 the fruit for a short time persistent. 



Bentham later (Benth. & Hook. Gen. PI. 3 : 1077. 1883) places Isachne 

 in the tribe Paniceae, immediately before Panicum, and Hackel (Engler 

 & Prantl, Pflanzenf. 2 2 : 33, 35. 1887) also assigns it to this position. 



Description. — Inflorescence paniculate ; spikelets obovoid to subglobose ; 

 glumes membranaceous, subequal, about as long as the fruits or at maturity 

 exceeded by these: lower floret perfect or staminate, its lemma and palea 

 indurated and similar in form and texture to those of the upper floret 

 (scarcely indurated and dissimilar in /. trachysperma Nees); both 

 florets (or fruits) plano-convex, obtuse, equal or nearly equal in size (the 

 lower often larger when staminate only), the pair usually remaining 

 attached together by the minute rachilla joint below the upper floret. 

 Perennials with simple or branching culms and flat blades, the species 

 confined to the tropics and warm temperate regions of both hemispheres. 



The lower floret often appears to be sterile (not perfecting a grain) in 

 some and fertile in other spikelets on the same panicle. When sterile 

 the floret is often longer and the lemma less convex than when fertile, 

 the spikelets on the same panicle thus having a somewhat diverse ap- 

 pearance. 



Several species of Isachne bear a superficial though striking resemblance 

 to species of the North American Panicum, subgenus Dichanthelium. 



25. Genus HETERANTHOECIA Stapf. 



Heteranthoecia Stapf in Hook. Icon. PI. 30 2 : pi. 2927. 1911. The 

 genus is based on a single species, H. isaclwioides Stapf (1. c. ) collected 

 in "Tropical Africa: Northern Nigeria; Nupc, in swamps Barter, 1348: 

 French Congo; Snussi Country (Chari oriental), at the sources of the 

 Ndelle River, Chevalier, 6825." It is not stated from which collection 

 the illustration was made. The genus differs from Isachne in having a 

 racemose panicle, the subsessile spikelets in short racemes, these arranged 

 along a common axis, and in having florets with lemmas dissimilar in 

 form and texture, though both fertile. Stapf considers the genus inter- 

 mediate between Isachne and Coelachne, the latter an anomalous genus 

 of the Old World at present placed in Aveneae. 



