40 



as such; but the non-extension of the branches of a panicle is not 

 of the slightest importance as a distinctive character, unless in 

 association with others, and the difference in the form of the anther 

 a very equivocal onej indeed, the latter is not an improbable 

 result of the constitutional defect by which the former is induced. 

 Apera interrupta is not, however, the only uncertain species which 

 the artist may figure and the author describe ; and its illustration, 

 whether species or variety, is equally useful, and essential to the 

 value of their work as one of general reference. 



Genus 16. CATABROSA. Whorl Grass. 



Gen. Char. Inflorescence loosely panicled ; branches spreading. 

 Spikelets stalked, oVate, one- to three-flowered. Glumes two, 

 unequal, concave, very obtuse, membranaceous, much shorter 

 than the spikelets ; the lower one-veined, oblong ; the upper 

 three-veined, obovate, twice as large, eroded at the apex. 

 Palese two, nearly equal, somewhat coriaceous, oblong ; the 

 lower three- veined, rounded at the apex; the upper two-veined, 

 truncated, and eroded. 



This genus, the typical and perhaps only true species of which 

 was formerly assigned to Aira, is readily distinguished from the 

 latter by the very obtuse termination of the glumes. The number 

 of perfect flowers in each spikelet is usually two, but occasionally 

 a third is found ; and sometimes even the rudiment of a fourth 

 flower presents itself, showing the tendency to profuse development 

 which characterizes the inflorescence of Glyceria, Poa, and some 

 other genera regarded as widely dissimilar. 



The name, from the Greek catabrosis, a gnawing, applies to the 

 eroded or irregularly-notched extremity of the glume. 



Catabkosa aquatica. Water Whorl Glass. Plate XXXV. 



Panicle pyramidal ; with alternate half whorls of spreading 

 branches. Leaves broadly linear, obtuse. 



Catabrosa aquatica, Beauvois. Generally adopted by modern bota- 

 nists. E. B. ed. 2. 110. Aira aquatica, Linnaus. E. B. 

 1557. Loudon, Encyc. 58. Poa airoides, DeCandolle. 



A common grass in watery situations, and about the banks of 

 rivers, ditches, and pools, where the flowering stems often rise 

 among the reeds and other herbage to the height of two or three 

 feet ; or, extending into the water, float upon the surface, sending 

 out fibrous rootlets from every joint, and becoming branched. 

 Leaves broad, flat, flaccid, sometimes very short, but not unfre- 



