MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA COLLEGE. 15 
The appended list," embodying all that is at present known to occur in the genus, in 
the fossil state, has been furnished by Dr. F. H. Knowlton, of the United States Na- 
tional Museum. 
While studying a collection of fossil plants with Mr. Hollick last winter, I detected 
among other new forms a Polygonum, remarkably distinct and well preserved. This col- 
lection was brought from Florissant, Colorado, a few years ago by Dr. Britton, and depos- 
ited in the Geological Museum of Columbia College. Nothing concerning this group has 
been recorded in North-American palaeobotany, but there can be no doubt about the 
member under consideration. It belongs to the subgenus Persicaria, and its nearest liv- 
ing relative is P. emersum. The resemblance to that species is striking in the characters 
of the stem, the way in which the petiole is joined to the ocrea, the leaf, and even in the 
forking of the secondary nerves of the leaf-blade. 
1 POLYGONUM ANTIQUUM Heer, Fl. Tert. Helv. 3: 184, f. 79, f. 27 (1859). 
POLYGONUM CARDIOCARPUM Heer, Fl. Tert. Helv. 3: 154, ¢. 155, f. 25-27 (1859). 
POLYGONUM CONVOLYULOIDES Conwentz, Fl. d. Bernst. 2: 48, ¢. 4, f. 23-26 (1886). 
POLYGONUM CUSPIDATUM Sieb. & Zuce. (fossil) Nathorst, Foss. Fl. Japans, Pal. Abhandl. 4: (30) 224, ¢. 10 (26), f. 16 
(1888). 
PoLyGoNuM Hyproprrekr L. ? (fossil) Heer, Urw. d. Schw. 496, 616 (1865). 
PoLYGONUM OTTERSIANUM Heer, Schweizerischen Naturf. Gesell. in Solothurn, Verhandl, 164 (1569). FI. Foss. Arct. 
2: pt. 3; ¢. 11, f. &, 14, 15; t. 12, f. 9-9” (1870). 
POLYGONUM PERSICARIA L. (fossil) Reid, Quart. Journ. Geol. Soc. 48: 358 (1892). 
POLYGONUM ROTUNDATUM Heer, Climat. et Vég. Tert. 45 (1861); Urw. d. Schw. 352, 706 (1865). 
POLYGONUM VIVIPARUM L. (fossil) Heer, Urw. d. Schw. 580, 760, ¢. 12, f. 13 (1865). Schroter, FL d. Eiszeit. 26, 35, 
t. 1, f. 43-44 (1882). 
POLYGONUM ? sp. Tasche, Ber. Oberhess. Gesell. Naturkunde, 4: 94 (1854). 
POLYGONITES DEPERDITUS Ett. Beitrige z. Kennt. Tertfl. Steiermarks, Sitz. Wien. Akad. 60: pt. 1, 58, ¢. 3, f. 15 (1869). 
POLYGONITES ULMACEUS Saporta. Ann. Sci. Nat. Bot. (V.) 3: 92, ¢. 3, f. 14 (1865). 
