al 
VASCULAR PLANTS OF NORTH DAKOTA 297 
PLATE XLV. 
EXPLANATION OF FIGURES. 
Fic. a. Brasenia Schreberi Gmel. Seedling illustrating habit of 
growth with thin aquatic submersed foliage and one quick floating leaf (W) 
when the seed germinates below the muddy bottom (BB'). Ep Elongated 
epicotyl. (S), Seed, (PR), Primary root. (W) Thick aérial leaf. The other 
habitats are similar to the following of Figs. (b), (c), and (d). 
Fic. b. Nuphar advena (Soland) R. Br. Seedling showing aquatic ' 
and floating leaves, and habit of the preceding. Parts labelled as in Fig. a. 
Fic. c. Same with seed germinating at the bottom on the mud but 
not buried. No elongated epicotyl developed. 
Fic. d. Same showing diminution in size of aquatic foliage when 
growing in shallow water with stronger light. 
Fic. e. Same with aérial thick foliage when growing in mud above 
the water line (WW’). 
Fic. f. Same the seed germinating upon instead of below mud. 
Foliage as in the preceding (Fig. e); no aquatic leaves developed. 
Fics. 1-10. Variations in aquatic leaf shapes of seedlings of Nym- 
phaea tuberosa Paine. The older leaves are broader with larger basal lobes. 
All plants about % to % natural size. Drawing diagrammatic, the 
petioles of all naturally longer, particularly in case of floating foliage. 
Petioles of the air-exposed plants (Figs. e and f.) drawn in natural propor- 
tions. All plants drawn from herbarium specimens collected at Bankson 
and North Bankson Lakes in August, 1915. 
ENUMERANTUR PLANTAE DAKOTAE SEPTEN- 
TRIONALIS VASCULARES.—IV. 
ENUMERAVIT J. LUNELL. 
The Vascular Plants of North Dakota.—IV. 
With Notes by J. Lunell. 
Sub-class 2. DICOTYLEDONEAE. 
D. C. Syst. I., (1818), also Prodr. I., p. 1. (1814). 
Order 16. SALICINAE. 
Bartling, Ord. Nat. Pl. p. 118. (1830.) 
Family 29. SALICINEAE L. Rich ex A. Rich. Nov. El. Bot. 
ed. 4, p. 560. (1828), also Lindley, Nat. Syst. ed. 2, p. 186. (1836). 
POPULUS Virgilius Ecl. IX. 41, Plinius XXIV, 8, Horatius, 
Seating. 11. 3. 
302. Populus tremuloides Michx. Fl. Bor. Am. 2. 243. (1803). 
