1992] ERTTER: POTENTILLA 435

1 Style + 1 mm long, swollen and rough-thickened at base, tapered to the apex; leaves tomentose underneath, toothed nearly to midvein; fell fields.

6 Leaves pinnate; leaflets 5-11, greener on upper side; achenes finely veined; widespread _.. P. pensylvanica 6 Leaves (sub)palmate; leaflets generally 5, silvery white on both sides; achenes smooth; California

........................................................................................................................................................................................................................... P. pseudosericea

A c k n o w l e d g m e n t s

Special t hanks are due to J i m Moref ie ld for his ass is tance do ing f ieldwork in the W h i t e M o u n t a i n s a n d for m a k i n g his per- sonal h e r b a r i u m spec imens ava i lab le ; to Noe l H o l m g r e n for his va lued c o m m e n t s a n d for p r o v i d i n g m e wi th the m a n u s c r i p t t r e a t m e n t o f I n t e r m o u n t a i n Rosaceae; to Jul ie Kie rs tead N e l s o n a n d J i m N e l s o n for ass is tance wi th f ie ldwork on ex-var , a l g i d a ; to R u p e r t B a r n e b y for h is ass is tance wi th the Lat in; to J i m Shevock for his rev iew o f the manusc r ip t ; to L i n d a V o r o b i k for yet a n o t h e r me t i cu lous i l lus t ra t ion ; to m y V W Fox for m a k i n g it up the last mi le f rom the Pa t r ia rch Grove ; a n d to the cura tor ia l staff o f the va r ious h e r b a r i a whose s p e c i m e n s were used for this s tudy (CAS, DS, D R , JEPS, MO, K, RSA, SBBG, UC, YU) .

Literature Cited

Clausen, J., D. D. Keck & W. M. Hiesey. 1940. Ex- perimental studies on the nature of species. I. Effect

of varied environments on western North Ameri- can plants. Carnegie Inst. Wash. Publ. 520, Wash- ington, D.C.

Ertter, B. 1989. Revisionary studies in lvesia (Ro- saceae: Potentilleae). Syst. Bot. 14: 231-244.

- - . 1992 [ 1991]. New combinations in Potentilla and Horkelia (Rosaceae) in California. Phytologia 71: 420--422.

Jepson, W.L. 1936. A flora of California. Vol. 2. Associated Students Store, University of Califor- nia, Berkeley, California.

Johnston, B.C. 1980. Studies of population vari- ability leading to a new classification of Potentilla sect. Multijugae (Rosaceae). Ph.D. dissertation. Universily of Colorado. Available from: University Microfilms, Ann Arbor, MI; publ. no. 8021589.

Morefield, J. D. & D. W. Taylor. 1988. Noteworthy collections: California. Madrofio 35: 164-166.

Peck, M.E. 1936. Six new plants from Oregon. Proc. Biol. Soc. Wash. 49:109-112.

Rydberg, P .A . 1898. A monograph of the North American Potentilleae. Mem. Dept. Bot. Columbia Coll. 2: 1-223.

Wolf, T. 1908. Monographie der Gattung Potentilla. Biblioth. Bot. 16(71): 1-714.

The 1992 Lawrence Memorial Award

J. Travis Columbus at the University Herbarium, University of California at Berkeley, is the recipient of the 1992 Lawrence Memorial Award. A student of Dr. Thomas Duncan, Mr. Columbus has undertaken a study of the generic-level taxonomy and evolution in the grama grasses and relatives (Gramineae: Cynodonteae: Boutelouinae). The proceeds of the Award will help support his field research, especially in Mexico. Commemorating Dr. George H. M. Lawrence, founding Director of the Hunt Institute for Botanical Documentation at Carnegie Mellon University, the semi-annual Award of $1,000 is made to an outstanding doctoral candidate for travel in support of dissertation research in systematic botany or horticulture or in the history of the plant sciences.