4 Mr. \^'ooDs on the Genera of European Grasses. 



some of the spiculoe are unproductive. These families are each divided into 

 two tribes, dependent on the axis or flower-stalk, which in the one is entire 

 and continuous, in the other toothed and jointed. The glumes or valves 

 of the calyx are, in the first tribe, inserted alternately; in the latter they are 

 described as " purallellc in.serfœ." Referring to the genera enumerated under 

 eacii head, in order to find the exact force of these terms, we find all our 

 one-tlowered grasses in the first, except A'^ardiis and Lepturus, together with 

 Bromus, Avena, Poa, Dac/i/fis, and some others; while Gli/ceri(i,Scter()chloa, 

 Fesfiicu, and others nearly allied are in the second. I confess myself completely 

 baffled by this result, and quite unable to discover what it is which is common 

 to one tribe and not to be fonnd in the other. The tribes are divided into 

 cohorts, as the spicuke are 1- 2- or many-flowered, and as the florets are indi- 

 vidually perfect or incomplete; and in the secouil family, according to the 

 position of the separated spiculee in the same or in different panicles or spikes. 

 The cohorts are variously divided into sections ; and these are again sub- 

 divided by means of the arms ; /. e. by their absence or presence, whether 

 awns or setae, rising y'/'o»? the extremity, near the extremity, from the back, 

 or from near the base of the corolla or stragnlnm. What I have already said 

 will show that this arrangement has the effect of widely separating genera 

 very closely allied. It has also the other, of bringing together genera whose 

 affinities are comparatively slight. Imperatd, for instance, stands in the same 

 section with Paspuluni and 3Ii I i inn ; Er'tanthus is placed with ('alanuigrostl^ 

 in another; Sj^orohohts, Ori/za, and Kjuipp'ia occur together in another. 

 Agrost'ts is divided into Agraulits, which is placed in the 3rd group; lilfa, 

 which is in the 6th ; jlgrostis in the 10th; and ^Iperu in the 13th; Plilenni 

 is with Spartina and C/i/<n-i.s in the 11th; Donax and Sesler'ta stand together 

 in the 27tli. The author frequently insists on his genera or groups being 

 natural, but he evidently only means by this that each has a clear and distinct 

 character. P. de Beauvois has introduced several new terms, and uses some 

 of the old ones in a peculiar way. Most of the writers on this part of botany 

 have acted in some degree in a similar manner. I will, therefore, before pro- 

 ceeding any further, exj)lain a few of the principal, both as used by others, 

 and as I have adopted them myself. 



Axis, with P. de Beauvois, is the part of the culm, above the upper knot. 



