116 Chase — Notes on Genera of Pankece. TV. 



There are several South American species, Panicum Schumannii Pilger 

 among them, at present insufficiently known to us, which belong in this 

 genus. 



9. Genus ECHINOLAENA Desv. 



Echinolaena Desv. Journ. de Bot. Paris 1 : 75. 1813. This genus is 

 based on a single species, E. hirta Desv. (1. c.) " Habitat in America 

 equinoxiali." The type specimen, bearing in Desvaux's handwriting the 

 name and date as published, is in the herbarium of the Museum d'His- 

 toire Naturelle at Paris. 



Echinolaena was recognized as a genus by Kunth (H. B. K. Nov. Gen. 

 & Sp. 1 : 118. 1816, Rev. Gram, 1 : 54. 1829, and Enum. PI. 1 : 171. 1833), 

 and by Trinius in his earlier work (Gram. Pan. 75. 1826), though later 

 (Mem. Acad. St. Petersb. VI. Sci. Nat. 3 : 2 230. 1834) he includes it under 

 his section Harpostachys of Panicum. Nees (Agrost. Bras. 127. 1829) 

 makes it a section of Panicum. Steudel follows Trinius' later disposition 

 of the genus, as does Doell (Mart. Fl. Bras. 2:' 2 179. 1877). Bentham 

 (Linn. Soc. Journ. Bot. 19 : 50. 1881) maintains Echinolaena as a genus 

 because of its having "the rigid single spike of some Chlorideae," and in 

 the Genera Plantarum (Benth. & Hook. Gen. PI. 3 : 1107. 1883), also, he 

 gives it generic rank. Hackel (Engler & Prantl, Pflanzenf. 2 : 2 35. 1887) 

 reduces it to a section of Panicum. 



Description. — Inflorescence of one dense and spike-like, or several rather 

 loose racemes ; spikelets in pairs, face to face, the primary short-pediceled 

 and perfect the secondary subsessile, abortive (sometimes developed, 

 rarely wanting ) , the back of the primary spikelet turned toward the axis 

 ( that is the back of the fruit turned from the axis), in two rows along one 

 side of a flat rachis and more or less divergent from it; fertile spikelets 

 laterally subcompressed, echinate, at least at maturity; glumes broad, 

 firm, acuminate-pointed, one or both echinate at maturity, the first 

 straight and as long as the spikelet or longer, the second boat-shaped or 

 becoming ventricose; sterile lemma broad, acuminate, enclosing a nearly 

 equal sterile palea and usually a staminate flower; fruit indurated, less so 

 than usual in Panicum, plano-convex, elliptical, the margins of the lemma 

 flat or inrolled at the summit only, a minute membranaceous wing or 

 spongy thickening on either side at base. Freely branching, more or 

 less decumbent or creeping herbs, the type species confined to the South 

 American tropics, another of widespread tropical distribution and a third 

 of Madagascar. 



The statement made by Bentham (Benth. & Hook. Gen. PI. 3 : 1107. 

 1883): " rhachi spicse rigida ultra spiculas producta," and which appears 

 from the Conspectus (page 1078) to express his chief reason for main- 

 taining Echinolaena as a valid genus, is found to be erroneous. The 

 uppermost spikelet in E. scabra (E. hirta), the one species Bentham 

 admitted to the genus, (as well as in E. polystachya) is strictly terminal, 

 the rachis not at all produced beyond its insertion. This uppermost 

 spikelet is solitary and usually erect, and the first glume is long-acuminate 



