TRIANDRIA— DIGYNIA. 73 



in the permanent hardened valves of the corolla, consti- 

 tuting a spurious seed-vessel, often accompanied with a 

 spiral or feathery, finally separating, awn ; albumen mealy; 

 embryo closely applied to the outer side of the albumen, 

 at the base, having a simple, shield-like, fleshy cotyledon, 

 as durable as the albumen, to which it is attached, under 

 the shin ; plumula external, simple, in a membranous 

 sheath of its own, from whence, when burst, the primary 

 leaves of the young plant are protruded. 



The genera of grasses are related to each other, as Mr. 

 Brown observes, in many different directions ; so that no 

 regular series can exhibit them all according to their na- 

 tural affinity. This able observer describes 3 principal 

 modifications of their fructification. 



In the first the calyx contains 1, 2, or many, Jlorets. When 

 the Jlo?'et is solitary, the outer valve of the corolla is at the 

 inside of the outer, or smaller, valve of the calyx ; when 

 there are 2 or more jlorets, they are either all perfect or 

 complete as to stamens and pistils ; or the upper, or in- 

 nermost, are gradually smaller, and less perfect, wanting 

 stamens, or pistil, or both. Most of the European ge- 

 nera come under this section, though they differ in their 

 inflorescence, as Agrostis, Aira, P/ileum, Alopecurus, Fes- 

 tuca, Poa, Avena, Broinus, Triticum, Hordeum, &c. These 

 genera, chiefly abounding in the temperate, and found 

 also in the frigid, zone, are of much rarer occurrence, if 

 not entirely wanting, in the torrid zones. 



The second section has either 2 Jlorets in each calyx, or by 

 suppression of valves, or of organs of impregnation, one 

 floret only; the more perfect, or durable, floret being al- 

 ways within, or next to, the inner valve of the calyx. To 

 this very natural tribe belong Holcus of Brown, (for which 

 I retain the name of Sorghum, see Rees's Cyclop, v. 33, 

 and which is not found in Britain,) Andropogon, Ischce- 

 mum, Saccharum, Panicum, &c, principally tropical 

 grasses, rarely occurring in the temperate, and scarcely at 

 all in the frigid, zones. 



The third section is characterized by having the interme- 

 diate floret united, or most perfect, while those at each 

 side are either neuter, or furnished at most with stamens 

 only. Mr. Brown considers this tribe as less natural, as 

 well as less extensive, than the two former. Hierochloe, of 

 which several species are found in the colder regions of 

 each hemisphere, is an example of it, and to this genus 

 Anthoxanthum bears a manifest relationship; seeDiandria 

 Digynia, p. 37. Mr. Brown traces an analogous struc- 



