7 
aft 
Mr. Woops on the Genera of European Grasses. 49 
with regard to these characters, as to almost every other, we have here a tribe 
in which they vary? Perhaps we may find in some of the tropical genera of 
Rottboelliaceæ an approach to the Paniceæ, reducing the arrangement of the 
whole family to a circular order. I have only three genera to notice, con- 
taining in ail but six species. 
1. Nardus. Spiculæ in two rows, on one side of a continuous rachis. Glumes 0. 
Outer palea keeled, tapering into a subulate point. Stigma 1. 
2. Psilurus. Spiculæ on opposite sides of the cylindrical but deeply channelled 
rachis. Glume 1, small. Outer palea membranous, awned ; inner as long, 
scariose. Stamen 1. 
3. Lepturus. Spiculæ imbedded in the channels of the cylindrical or prisma- 
tical fragile rachis. One-flowered, with an interior rudiment. Glumes 
l or 2, opposite to the rachis, and as long as the scariose paleæ, 
Psrrunus nardioides seems well separated from Nardus. Schrader put it 
with Rottboellia; Palisot de Beauvois called it Monerma. I take it for granted 
that Psilurus, the name given to it by Trinius, and adopted by Mertens and 
Koch, as well as by Kunth, is the most ancient. The spiculæ are placed some- 
what obliquely, and the glume is not exactly opposite to the rachis, the abortive 
floret on one side appearing conspicuously from underneath it. 
Leprurus contains the 4 European species which were formerly given to 
the genus Rottboellia. It has only one spicula at each joint of the rachis, and 
this contains one perfect, and a superior imperfect floret or rudiment. The 
true Rottboellia has 2 spiculæ at each joint, one of which is tabescent, and the 
perfect spicula has one perfect and an inferior imperfect floret or rudiment. 
Before concluding this essay I will offer an artificial arrangement of the 
Grasses, founded chiefly on their inflorescence, which seems to yield the most 
distinct and definite characters, and is therefore best adapted to facilitate the 
researches of the student, and enable him to determine to what genus any 
plant under examination may belong. With the same object in view we may 
observe, 
That the spikes are fingered in Cynodon, Dactyloctenium, Digitaria, and in 
- 
some species of Andropogon. 
VOL. XVIII. H 
MISSOURI 
BOTANICAL 
GARDEN. 
