BARTRAM: BOTANIZING IN SOUTHERN ARIZONA 239 
walker who steps unguardedly into these precincts. The spines 
penetrate shoe leather like a steel needle and refuse to be with- 
drawn. Nature guards her wards well in these desert places and 
the animals, profiting by the example, guard their dens with a 
pile of these bristling joints, carried one by one at a cost easy 
to be reckoned by anyone unfortunate enough to have brushed 
against a stem in an unguarded moment. 
Along the creek issuing from the canyon are many waifs 
from the higher zones, such as Juniperus scopulorum, Yucca 
baccata, Quercus Emoryi, Q. oblongifolia and Q.hypoleuca, but it is 
among the rocks on sheltered slopes in the canyon that we find 
the earliest flowers. Herethe fairy dusters, Calliandra eriophylla, 
are just spreading their delicate balls of pink bloom, and clumps 
of Lesquerella purpurea are established in many congenial crev- 
ices. Hermannia paucifiora with the flowers well concealed 
among the matted woody stems is easily overlooked, and a form of 
Anislotus puberulus with showy golden yellow flowers and nearly 
leafless stems helps to brighten the otherwise barren ledges. 
Notholaena Lemmoni grows abundantly among the rocks of a 
dry sunny slope, while the shaded crevices and fissures give 
harbour to such species as Pellaea mucronata, Cheilanthes Lind- 
heimert and various mosses, among which Tortula inermis, T. 
ruralis, Barbula Manniae and B. chloronotus are the most in 
evidence. Where almost any other living thing would wither and 
perish Agave Parryi and Dasylirion Wheeleri spread over the 
ledges and boulders in flourishing clumps that lend a charac- 
teristic touch to this unique landscape. 
The region about Picture Rocks was another productive 
locality that proved interesting enough to warrant trips at 
intervals of about ten days. Some twelve miles west of Tucson, 
near the far end of the Tucson Mountains in a broad gully 
fronting the old Indian pictographs, from which the place takes 
its name, Anemone sphenophylla was just coming into bloom on 
January twelfth, white clusters of Dryopetalon runcinatum 
brightened many of the damp rock fissures, the trim little 
Thysanocarpus amplectens grew sparingly in nearly every 
depression where sufficient soil had accumulated to support a 
short span of life during the season of winter rains, while various 
winter annuals, such as Lepidium lasiocarpum, Draba cuneifolia 
and Amsinckia Menziesii, were scattered sparingly in the shelter 
