357 
leaves linear-lanceolate to narrowly linear, two to four and a half 
inches long, short-petioled, ciliate-margined, punctate; sheaths 
truncate, smooth, one inch long; flowers light rose-color, in dense 
spikes, which are one inch long and erect; calyx five-parted ; 
stamens six to eight; style two-parted; long; achene lenticular, 
broadly ovate, long-pointed, reticulated and dull. 
Mexico: Sonora (E. K. Smith), San Luis Potosi (Schaffner, 
882), Jalisco (Pringle, 5186). 
This species is most closely related to P. Pennsylvanicum, 
from which, however, it differs in a marked degree in its leaves 
and flowers, but especially in its broadly ovate and dull achene. 
21. POLYGONUM PRINGLEI, n. sp. 
Plant mostly erect, branching, two to five feet high, the lower 
part of the stem inclined to be decumbent and to root at the 
nodes, glandular throughout, peduncles and pedicels densely 
glandular. Leaves linear-lanceolate to linear, two to four inches 
long, subsessile, acuminate, ciliate-margined, minutely punctate ; 
sheaths loose, slightly rough; flowers light pink, in rather loose, 
thick, cylindrical spikes, which are one inch long, or less, and 
erect ; calyx 5-parted, stamens generally eight; style two or three- 
parted, rather short; achene lenticular or concave-triquetrous, 
broadly obovate, short-pointed, smooth and shining. 
Mexico: San Luis Potosi, Las Canoas (Pringle, 5183). 
This species collected by Mr. Pringle, is a beautiful and pe- 
culiar plant. Its stem is very glandular down to the root. The 
spikes are usually thick and the flowers of a light-rose color. As 
is the case in a number of other species, P. Pringlet has atwo or 
three-parted style, and consequently lenticular and triquetrous 
achenia. In aspect this species is most nearly related to P. /apa- 
thifolium. 
22. POLYGONUM LAPATHIFOLIUM, L. Sp. Pl. 360 (1753). 
P. Pennsylvanicum, Curt. Fl. Lond. t. 73 (1777), not ae 
P. nodosum, Pers. Syn. i. 440 (1805). 
P. utriculatum, Remy in Gay, FI. Chili, v. 267 (1849). 
This species seems to be introduced throughout North Amer- 
ica, Mexico and West Indies. Itis remarkably variable. Extreme 
forms seem to furnish sufficient characters to hold P. nodosum 
separate from P. lapathifolium, but the close study of a large 
‘number of specimens seems to indicate that none of the charac- 
‘ters maintain themselves. 
