—74— 



the carinal hole, the vallecular being comparatively weak, not 

 reaching the vallecular. hole, the green parenchyma forming an 

 oblong mass above the central hole and between the contiguous 

 carinal bast-masses. 



A particularly variable species or group of forms of different 

 aspect exteriorly, but separated from the former group by hav- 

 ing the teeth articulated to the sheaths, not leaving a persistent 

 base in falling, and especially in the arrangement of the bast as 

 previously mentioned. The type is European and is character- 

 ized by two rows of tubercles on the ridges and by long amplia'ed 

 sheaths as in laevigatum. I have seen nothing from America 

 to match it, and all our forms so referred really belong to 

 robustum. After comparing a large series of American and 

 European plants I have concluded that the latter species is not 

 specifically distinct. According to the author, its characters are 

 the shorter sheaths, larger size, and cross-bands of silex rather 

 than two rows of tubercles, but the variety attnc has the size and 

 sheaths of European hiemale, differing by having bands of silex 

 on the angles. The variety pumilum is smaller than most of my 

 specimens of variety viride, smaller than some forms of varie- 

 gatum, yet has the bands of robustum. Variety Calif ornicum 

 has the sheaths and appearance of robu.stum, is often larger than 

 that form, and has two rows of tubercles and leaves centrally 

 grooved. The European Moorei with large ampliated sheaths 

 has its counterpart in var. intermedium, only the latter has 

 bands while the former has usually two rows of tubercles. 

 Finally, the bands on which the species mainly rests are not 

 constant in our species nor are the tubercles in the European. 

 Of the latter Milde. who regarded robustum as a sub-species, 

 quotes specimens with cross-bands from several European locali- 

 ties, while var. Moorei not rarely shows them. Var. interme- 

 dium and some others occasionally show tubercles and leaves 

 centrally grooved, while branches of any of the group bear 

 grooved leaves as a rule. Variety Calif ornicum often bears 

 bands as well as tubercles, and typical robustum not rarely bears 

 a few tubercles. 



Although typical robustum differs markedly from typical hie- 

 male- it will be seen from the above that not one character is 



