BRIEFER ARTICLES. 



THE TRICHOME STRUCTURES OF ERODIUM CICUTARIUM. 



(with fourteen figures) 



The results of observations made by the present writer on the tri- 

 chomes of Erodium are so different from those recently published in 

 this journal^ that it has seemed worth while to present them in some 

 detail. About four more or less distinct forms of tfichomes were 

 found, some of these are glandular, others non-e^landular. 



The trichomes of the hypocotyl are chiefly two to three-celled 

 short filaments tipped with a bulbous glandular cell {Jigs. /, 2, j)- 

 Those of the cotyledon are various ; thus the petiole bears some very 

 short glandular hairs (Jig. 6) smaller than those of the hypocotyl, also 

 kind with a long somewhat tapering basal cell {Jig- 4)- I^^ addition 

 to these glandular hairs there are some large unicellular hairs {Jigs^S^ 7) 

 scattered here and there among the others. " The blade of the cotyle- 

 don has in the basal sinus some of these same simple hairs. On other 

 parts of the blade the hairs are glandular. Most of them are short 

 {Jig, g), but there are also some longer ones {Jig^ S) similar to some ot 

 those on the petiole {Jig, 4), 



The ordinary foliage leaves are somewhat different from the coty- 

 ledons in the trichomes they bear. The petioles have a great number 

 of small glandular Hairs {fig- id)^ and in some specimens not a few 

 longer hairs {fig* 13)- Often these longer ones consist of five or six 

 cells. In every case the proximal cell is far larger than the others. A 

 thick-walled, rough tuberculate trichome {fig^ 1 1) is also present. The 

 leaves are pinnately divided and, as would be expected, the rachis has 

 about the same trichome structures as the petiole. The long tubercu- 

 late form {fig* 12), however, is somewhat more common than the 

 others, and is here longer than on the petiole. Sometimes these tuber- 

 culate structures are two-celled, but this is not a common occurrence. 

 Scattered glandular hairs are also present like those seen on other 

 parts {figs. 8, id). The leaf blades bear many short tuberculate hairs. 

 These are of different sizes. Fig. 14 shows the most usual size and 



'Preston, Carleton E., Two instructive seedlings. Bot. Gaz. 33 '-^S^- ^9°^* 



140 [AUGUST 



