22 Rhodora [FEBRUARY 
eastern Vermont, eastern Massachusetts including Essex, Middlesex, 
Suffolk, Norfolk and Barnstable Counties, Rhode Island, eastern and 
central Connecticut, Long Island, New York City, regions of the 
lower Delaware River, lower Susquehanna River, Chesapeake Bay, 
and westward to Wisconsin, Missouri, Nebraska, and in Oregon. 
In most of these regions the soil is derived from granitie or sandy 
sources, and the element of lime is conspicuous by its absence. To 
this species Pursh's name occidentalis, excluding the synonym Elodea 
canadensis Michx. and the part of the description drawn from it, is 
applicable, and as it is the first name for it within the specific cate- 
gory, the new combination is made here. The more northern Æ. 
canadensis is known to the writer from a station in the mountains of 
Virginia, and another in Kentucky, but these are the only stations 
south of southwestern Connecticut. 
For this plant, in the eastern part of its range, Rydberg takes the 
name Serpicula verticillata, B. angustifolia Muhl. and makes the 
specific combination. This varietal name angustifolia Muhl., al- 
though a nomen subnudum, seems to be properly applied to this 
plant, but if it is considered a species, as by Dr. Rydberg and the 
writer, the varietal name must be replaced by the first specific name, 
occidentalis Pursh, which was the first name in the proper category. 
From this species Rydberg? distinguishes Philotria minor (Engelm.) 
Small which has similar staminate and pistillate flowers, but differs 
in having the “Leaves 5-8 mm. long; sepals and petals 1-1.5 mm. 
long" instead of * Leaves 1 cm. long or more; sepals and petals 1.5-2 
mm. long" and growing in the central valley of the United States 
instead of in the northern Atlantic states. There is a good specimen 
of Engelmann's Udora verticillata ? minor from St. Louis, 1845, in 
the Gray Herbarium. This was first published? in synonomy under 
Anacharis Nuttallii Planchon. It was the basis of Philotria minor 
(Engelm.) Small: There is no wide gap between the ranges of 
occidentalis and minor nor can the writer distinguish any differences 
in the flowers or leaves. Consequently minor is placed in the syn- 
onomy of occidentalis. 
In an article on the “ Morphology of Elodea canadensis,” Robert B. 
Wylie® gives some important details of the phenomena of pollination. 
1! Muhlenberg, Henry, Cat. Pl. N. Am. 84 (1813). 
? Bull. Torr. Bot. Cl. xxxv. 463-5 (1908). 
3 Pringsheim's Jahrb. wissen. Bot. i. 465 (1858). 
4 Small, J. K., Fl. S. E. U. S. 47 (1903). 
5 Wylie, Robert B., Bot. Gaz. xxxvii. 11 (1904). 
