382 TRANS. ST. LOUIS ACAD. SCIENCE. 



covers the acorn scarely one-half, usually three-fourths, and occasionally 

 entirely; the margin is profusely or sparsely fringed. — Throughout the 

 north-west, north of the Missouri river, a low scrubbj'form is found, which 

 might be designated as var. depressa, as it is undoubtedly the obtusiloba 

 ;3. depressa, Nutt. gen. 2, 215, which has smaller leaves and much smaller 

 acorns than the species, but is clearly a form oi macrocarpa. 



3. ^. Mickauxti, Nutt. gen. 2, 215, excl. syn. — The figure of Michaux, 

 quoted by Nuttall, refers to ^. bicolor, and none of his figures represent 

 our plant. Elliott adopts Nuttall's name, but Chapman as well as DeCan- 

 dolle consider it a form of Prinns. ^. Prinus was described by Linnaeus 

 with foliis obovatis utrinque acuminatis, which sufficiently well agrees 

 with all the forms of Pr/>/?<5 proper. Our plant is distinguished by having 

 the leaves obtuse, or mostly cordate, at base ; thicker, more leathery, and 

 tomentose, on the lower side ; and the male flowers lo-androus. All the 

 forms of Prinus proper have a very deciduous pubescence on the lower 

 side of the leaf, which is acute or acutish at base. 



4. «^. Prinus., Lin., would then comprise Michaux's varieties, palustris, 

 monticola, and acuminata. 



5. ^. undulata, Torn, has been treated of in the introduction to this 

 paper; the different forms, there also enumerated, are — «. Gambelii (.^. 

 G«w(Je///V, Nutt. and probably ^. Drun)mondii,l^\ehm.^; (i. Gunnisoni 

 (_^. alba, var. Gunnisoni, Torrey) ; }. Jamesii, Torrey's original plant, 

 figured in Ann Lye. N.Y. 2, t. 4 ; the original figure reproduced with slight 

 alterations in Nuttall's N. Am. Sylv. 1, t. 3; (5. Wrightii, often confounded 

 with ^. Emoryi, and apparently one of the forms comprised by Liebmann 

 in his ^. pun gens. ^. oblong/folia, Torr., and .^. grisea Liebm., seem 

 to be forms with more or less entire leaves ; or the latter may perhaps have 

 to be referred to the Mexican .^. microphylla. 



6- ^. dumosa, Nutt., N.Am. Sylva, i, p. 7; Torrey, Bot. Mex. Bound, 

 p, 207. ^. acutidens, Torr. ib. tab. 51, is a larger form of the same. ^. 

 berberidifolia, Liebm., DeProd. 16, 2, p. 36, seem to belong here either 

 entirely or at least in part. A shrub of the southern part of California, 

 often very squarrose, sometimes with slender and erect branches ; leaves 

 oval, obtuse, often cordate or obtuse at base, spinous-dentate or sometimes 

 entirely dark green above, hoary tomentose or pubescent below, from ^ to J 

 or sometimes i inch long; fruit sessile; cup strongly tuberulate, black, 

 between 2 and 6 lines in diameter; acorn large for the size of the plant, 

 oval, or small and narrow. 



7. ^. Emoryi, Torr. Emory Rep. 1848, p. 151, t. 9, ^. kastata, Liebm. 

 Quite distinct from ^. undulata, var. WrigJttii, ^W^ch is often confounded 

 with it; the peduncled acorn of Torrey's figure may belong to that form 

 of undulata. This pretty Arizonian species was collected by Emory in 1846, 

 and soon afterwards by Wright, and then not again until Dr. Rothrock, 

 a year or two ago, brought back fine specimens from Lieut. Whipple's Ex- 

 pedition. The leaves are not roundish or oval and pale as in Wrightii, 

 but lanceolate, cordate at base, and dark green ; the acorns in all the 



