82 ERYTHEA. 
17. Hotopiscus piscotor (Pursh), Maxim. Aduot, Spir. 
150. Spirea discolor, Pursh. Common among rocks and 
in thickets along the highest ridges. 
18. CERCOCARPUS BETULEFOLIUS, Nutt.; Hook. Icon. t. 
322. The Mountain Mahogany; not very common, and ina 
shrubby form only. 
19. PorEnTILLA GLANDULOSA, Lindl. Bot. Reg. t. 1583. 
20. Rosa Catrrornica, Ch. & Schl., Linnzxa, ii. 35. At 
the Joaquin Springs. 
21. Rvusus virirotius, Ch. & Schl. 1. c. 10. The wild 
Blackberry; not seen except at the Aquarius Springs. 
22. AcER MACROPHYLLUM, Pursh, Fl. i. 267. Toward the 
Joaquin Springs. 
23. AscuLus Catirornica (Spach), Nutt.; Torr. & Gray, 
FI. N. Am. i. 258. 
4. Ruus piversiLopa, Torr. & Gray, Fl. N. Am. i. 218. 
Poison Oak; very little seen. 
25. RHAMNUS TOMENTELLA, Benth. Pl. Hartw. 303; Greene, 
Fl. Fr. 88. Common on dry exposures looking southward; 
less tomentose than on the foothills of the Sierra. Also in 
wet ground bordering the Joaquin Springs, where it shows 
so little pubescence, and so much more ample foliage, that it 
was at first thought to be R. Californica; but an inspection 
with lens reveals the peculiar pubescence of R. tomentella; 
and, as Mount Hamilton belongs to dry interior region, and 
not to the Coast Range, it is this, rather than R. Californica 
which one would naturally expect to find here. 
That no trace of the large representative Rhamneous genus 
Ceanothus should have been observed anywhere on this 
mountain is a very noteworthy fact; especially since its 
species form the bulk of the brush-wood in so many places 
both of the Coast Range and the Sierra. 
26. Croton sreTiaerus, Hook. Fl. Bor.-Am. ii. 141; 
Greene, Fl. Fr. 89. Near the summit, where it may have 
