SUPPLEMENT 



though not always, strike the prominent stigmas on entering, and 

 while the stigma stands sometimes above the anthers when the 

 flower is expanded, it is probably self pollinated as the flower closes. 

 I have seen the stamens resume their vertical position in from eight 

 to twelve minutes, but they have rarely opportunity to do this on ac- 

 count of the frequency of guests. The rarer, but more showy, ma- 

 genta cactus, Opuntia basil aru t Kngl., has more active stamens, and 

 a stigma that is always quite above them. The smaller greenish flow- 

 ers of Cereus Emory 'i, Englm., are so narrow that a large bee must 

 cling to the ample stigma in order to collect the pollen, and so he is 

 sure to effect cross pollination. 



Collections of cacti are so common in Southern California that 

 many other interesting features may be observed. The night-bloom- 

 ing Cereus climbs by branching rootlets; the expansion of its great 

 exquisite flowers is a process well worth watching. Two species of 

 Mesembryanthemum are common on our beaches. Two genera of the 

 Crassulaceae, Sedum and Cotyledon, are rather widely distributed in 

 rocky places; the species are difficult to determine. The chamisal, 

 Adenostoma fasciculatum, H. & A., has its short, spine-like leaves in 

 fascicles or clusters. Like most Rosaceae, it provides honey, and is much 

 cross pollinated by bees although its flowers seem quite capable of 

 self pollination. 



The Eriogonums have already received considerable attention in 

 Chapters III and XIV. Their pollination is interesting; the follow- 

 ing is true of E. fasciculatum and of several other species with large 

 flower clusters. The perianth consists of six sepals; the nine stamens 

 erect themselves, a few at a time, holding their anthers, which are of 

 contrasting color, upward during dehiscence; after the anthers have 

 all shed their pollen and fallen off, the three styles, which have been 

 tightly curled down in the centre, straighten and hold their stigmas 

 in the same position before occupied by the anthers. The perianths 

 do not fall after the pollination of the flowers, but change to a con- 

 trasting color, those of the white species to pink, the yellow ones to 

 red, and so add to the attractiveness of the cluster. The amount of 

 honey secreted is sufficient to attract throngs of bees of all sizes, al- 

 though they must share it with all sorts of small insects. 



The dodder, Cuscuta, is parasitic on many of our native plants; 

 there are several species, difficult to determine. The little flowers 

 are somewhat fragrant and have considerable honey; at first their an- 

 thers are held away from the stigmas, but later on the stamens bend 

 to the centre, and apply their pollen to the stigmas. 



Pentstemon cordifolius, Benth., the Pentstemon with cordate 



118 



