IOWA ACADEMY OP SCIENCES. 
151 
it to say here that Duval, Jouve^^, Hackel^a, Gllntz^g, Samsoe, 
Ltindj^ and Beal^g have made valuable contributions. 
Theo. Holm^^g has studied Uniola latifolia, U. gracilis, U. nit- 
ida, U. paniculata and U. Palmeri, Distichlis, Pieurogogon and 
Leersia. 
Prom a study of some of the species of Uniola growing under 
widely different conditions, he concludes, that of the five spe- 
cies, the genus show anatomical structures by which they may 
be easily distinguished. 
He says of the genus Distichlis, that, “Considered altogether, 
the anatomical structure of the leaf in the genus Distichlis is 
very uniform, and it does not seem possible to give any 
special characters by which either of the varieties or the sup- 
posed species thalasica and prostata may be distinguished from 
the species maritima', because we have seen that male and 
female specimens of this last show variations among them- 
selves nearly equivalent with the differences in the two varie- 
ties and subspecies.” Of Pleuropogon, he says: “Considering 
now these three species of Pleuropogon together, it is evident 
that they are, in spite of their great similarity, easily distin- 
guished from each other” by certain anatomical characters 
taken from leaf blade. 
THE GENUS SPOROBOLUS. 
The species of the genus Sporoholus are nearly all western or 
southern. Those occurring in Iowa are characteristic western 
plants and well adapted to dry climate conditions. The follow- 
ing species of Sporoholus were studied: Sporoholus heterolepis 
Gray; S. cryptandrus Gray; S. Hookeri, S. vagincefloo^us. 
SPOROBOLUS HETEROLEPIS. 
The epidermal cells (e) are rectangular in shape, with a 
strongly developed cuticle (c); they vary but little in size. 
The bulliform cells (b) occur between each mestome bundle (m), 
except between the last few at the tip of the leaf, where it is 
occupied by the streome (st.). The bulliform cells occur in four 
or five rows, a large central cell and three or four smaller cells 
Histotaxie des feuilles de Grraminees. 
12 Monographia Festucarum Europaearum, 1882. 
13 Untersuchungen ueber die anatomische Structur der Gramineenblaetter, etc. 
Inaug. Dissert. Leipzig, 1886. 
11 Vejledning til at kjende Graesser i blomterlos Tilstand, Kjobenhavn, 1882. 
15 Grasses of North America for farmers and students. 
16 A study of some anatomical characters of N. America Gramineae. Bot. Gazette, 
Vol. xvi. p, 166, 217, 275. 
