54 ME. G. BENTHAM ON QEAMINE^. 



leave it uncertain wiietlier it is a glume or a palea — ttat is, whether 

 it be attached to the end of the rhachilla or primary axis of the 

 spitelet, or to a secondary or floral axis reduced to a mere point. 

 There are theoretical reasons in favour of both explanations, and 

 actual observation is insufficient for determining the point. The 

 first of these views has appeared to me the most plausible ; and I 

 have accordingly in my diagnoses and descriptions treated the 

 scale in question as the flowering glume, and considered the 

 palea as deficient, as it certainly is in some Andropogonese and 

 Agrosteae. In this view the technical distinction between the 

 two tribes would be, that the Oryzese have 2, 4, or rarely 3 glumes, 

 all above the articulation of the pedicel, and the Phalarese 4, 6, or 

 rarely 5 glumes, the lowest pair persistent below the articulation 

 of the rhachilla. Oryzese thus characterized may be thought as a 

 whole to be a rather artificial tribe ; but they are divisible into 

 two much more natural groups or subtribes — Zizaniea, tropical or 

 American genera, often semiaquatic plants, with a loose in- 

 florescence and stamens often, but not always, more than three ; 

 and AlopeourecB, European or temperate Asiatic or African genera, 

 with a dense spike-like inflorescence and stamens never more than 

 three. 



ZizaniesB includes the following eight genera : — 



1. Htdeochloa, Beauv., a single species from Carolina, and 

 there apparently rare, diifering from Zizania chiefly in the inflo- 

 rescence reduced to few-flowered spikes, of which the terminal 

 one male and pedunculate, the lower ones female and sessile in 

 the axils. 



2. ZizANiA, Linn., comprises two species, or according to others 

 two genera, each with two or more species. As a whole, the genus 

 is a natural one, well characterized by the unisexual spikelets in 

 an androgynous panicle, each one with only two glumes and the 

 males with six stamens. The typical Z. aquatiea, Linn. {Sydro- 

 fyrwm. Link), has the lower part of the panicle more spreading 

 and male, and the upper part narrow and female ; it is widely 

 spread over North America, and includes the East-Eussian and 

 Japanese Z. latifolia, which is absolutely identical with some 

 North-American specimens. The other species, Z. miliacea, 

 Kunth {Zizaniopsis, Doell), has the male and female spikelets 

 more mixed in the panicle, the awns shorter, the styles more 

 connate, and the grain broader — characters which appear to me 

 quite insufficient for generic distinction. It is a North-American 



