DEPARTMENT OF BOTANICAL RESEARCH. 101 



larity to the other species. The fruits of 0. leptocaulis, like those of 

 the cholla, are often sterile. More than half of them contain only 

 small shriveled rudiments of seeds. The fruits of this species do not 

 remain attached as long as those of 0. fulgida, though some of them 

 may stick to the parent plant for a year after they are mature. 



When freed from the plant, the fruits of 0. leptocaulis root promptly 

 and apparently may give rise to new plants as readily as those of 

 0. fulgida do. 



Fruits and the peculiar deciduous joints of 0. leptocaulis, when placed 

 on damp soil in a cool laboratory, developed roots 3 cm. long in 5 

 weeks (in July) and the new shoots on the same joints were then 2 cm. 

 long. External examination and sections showed that roots may arise 

 from the margin of any areola of the buried part of the fruit or joint. 

 In other cases a root may arise from the center of the scar of the broken- 

 off stalk of the joint and from a direct continuation of the axis of the 

 latter, with the vascular bundles of the two intimately connected. 



The deciduous joints above mentioned are formed in dozens on the 

 tips of the long shoots of this slender-stemmed Opuntia. These joints 

 are 6 or 7 mm. in diameter, from 2 to 5 cm. long, and are arranged on 

 the long shoots like the fruits, among which they frequently appear. 

 The general appearance and number of areolae on the shorter of these 

 shoots, together with their arrangement, suggest that they may really 

 be regarded as phylogenetically derived from sterile fruits. It is 

 expected that examination of a large number of specimens will deter- 

 mine whether there exist structures intermediate in character between 

 these propagula and the sterile fruits that are readily recognizable as 

 such. The development of 4 or 5 flowers, from the more terminal 

 areolae of certain of these propagula which remain attached to the plant, 

 is perhaps what should be expected if they are regarded as purely 

 vegetative branches. The form of the persistent propagulum, however, 

 with the grouping of the flowers at its tip, gives quite the appearance of 

 a flower-bearing fruit of 0. fulgida. 



Morphological Studies of Carnegiea gigantea, by C. E. Bessey. 



Structural studies were made of the flower-buds and flowers of the 

 sahuaro, and photographs were obtained of the latter when fully open. 

 These were produced upon a branch 1 meter long, sent from the Desert 

 Laboratory to the plant-houses of the department of botany of the Uni- 

 versity of Nebraska. The development of the buds was followed day by 

 day until they opened (in the forenoon), reached their maximum 

 (about midday), and then slowly closed (by nightfall). In the new 

 habitat the branch produced four sets of flowers, three in May and one 

 in September. Repeated attempts to secure fruits by artificial 

 pollination failed. Advantage was taken of the opportunity afforded 



