MALACEAE. 193 



4. SORBUS L. MOUNTAIN ASH. 



i. Sorbus scopulina Greene. (Pyrus sambucifolia T. & G. ; not C. & S.) 

 In moist ground and hillsides from Alb. and Wash, to Colo, and Utah. 

 Alt. 5000-10,000 ft. Near Ouray; Upper La Plata Canon; Four-Mile Hill, 

 Routt Co.; Pagosa Peak; Box Canon, west of Ouray; Victoria; North 

 Cheyenne Canon; west of Palmer Lake; Buffalo Pass; Empire; Rabbit-Ear 

 Range, Routt Co. 



Family 68. AMYGDALACEAE Reichenb. PLUM FAMILY. 



i. PRUNUS L. PLUMS, CHERRIES. 



Flowers in lateral scaly umbels or corymbs, expanding with or before the leaves. 

 Pits of the fruit flattened; leaves convolute in vernation. i. P. americana. 

 Pits globose, not flattened ; leaves conduplicate in vernation. 



Low, decumbent shrubs ; inflorescence strictly sessile and umbel-like. 



2. P. Besseyi. 

 Erect shrubs or trees ; inflorescence corymbiform, more or less peduncled. 



3. P. pennsylvanica. 

 Flowers in long racemes, ending leafy branches of the season. 



4. P. melanocarpa. 



1. Primus americana Marsh. Along streams from N. Y. and Mont, to 

 Fla. and Colo. Alt. 4000-7000 ft. Boulder; foot-hills of Larimer Co.; Wal- 

 senburg; plains near Denver; gulch west of Dixon Canon; vicinity of Horse- 

 tooth; Rist Canon; Horsetooth Gulch; Trinidad; Cache la Poudre; Manitou. 



2. Primus Besseyi Bailey. On sand-hills from N. D. to Kans. and Colo. 

 Alt. 4000-5500 ft. Ft. Collins; foot-hills west of Ft. Collins; north of 

 La Porte; Horsetooth Mountain; Black's Lake. 



3. Prunus pennsylvanica L. f. In rocky woods and on hillsides and along 

 streams from Newf. and N. D. to Ga. and Colo. Alt. 4000-9500 ft. Estes 

 Park, Larimer Co. ; Ft. Collins ; Minnehaha ; gulch west of Pennock's ; 

 Pike's Peak; Rist Canon; Stove Prairie Hill; Redstone; mountains between 

 Sunshine and Ward; Eldora to Baltimore; Manitou. 



4. Prunus melanocarpa (A. Nels.) Rydb. (P. demissa Torn, in part; not 

 Walp. ; Cerasus demissa melanocarpa A. Nels.) On hillsides from N. D., Alb., 

 and B. C. to N. M. and Calif. Alt. 4000-8000 ft. Lake City; foot-hills, Lari- 

 mer Co.; Estes Park; Mancos; Cheyenne Canon; butte, five miles southwest 

 of La Veta; Cucharas River, below La Veta; Dillon Canon; Trinidad; Ft. 

 Collins; Cache la Poudre; Bosworth's ranch; gulch west of Pennock's; 

 Horsetooth Gulch; Dixon Canon; Purgatory River, Trinidad; Pinkham 

 Creek. 



Family 69. MIMOSACEAE Reichenb. MIMOSA FAMILY. 



Valves of the pod not separating from the continuous margin, not prickly ; stems 

 erect, unarmed. i. ACUAN. 



Valves of the pod separating from the continuous margin ; pod 4-angled, prickly ; 

 stems prostrate, prickly. 2. MORONGIA. 



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