POLLINATION. 



27 



a considerable number of short twigs to which the flowers are attached, 

 the whole contained in a sheath at first entirely closed, but which finally 

 ruptures, disclosing the flowers. (PI. VII, figs. 1 and 3.) The Arabs 

 cut the male flower clusters from the trees shortly before the flowers 

 have fully opened, at a somewhat earlier stage than shown in Plate 



VII, fig. 1. The separate twigs to which the male flowers are attached 

 (PL VII, fig. 3, twig below) are from 4 to 6 inches long, and bear 

 anywhere from 20 to 50 male flowers, each 



containing 6 anthers full of pollen. One of 

 these twigs suffices to pollinate a whole 

 female flower cluster, and to bring about the 

 development of a bunch of dates. 



The female flowers, like the male, are borne 

 inside of sheaths which are at fir^t entirely 

 closed. Finally the sheath is split open by 

 the growth of the flowers within (PI. VII, 

 fig. 2, twig to left), and at this stage pollina- 

 tion is accomplished. The two tips of the 

 cracked-open sheath are separated and the 

 cluster of female flowers pulled out. (PL 



VIII, fig. 3.) A twig of male flowers is then 

 inserted into the cluster of female flowers 

 and tied in place with a bit of palm leaf or 

 with a string. (Fig. 2 and PL VIII, fig. 4.) 

 This completes the operation of pollination. 

 The fruit cluster soon begins to grow rapidlv, 

 and in a few weeks the piece of palm fiber 

 or thread with which the male flowers are held 

 in place is broken by the pressure of the grow- 

 ing fruit cluster. Such a fruit cluster, still 

 confined, but which will shortly break the 

 fiber, is shown in figure 1 (p. 16). 



In the Algerian Sahara the date begins to 

 flower in April, and sometimes produces 

 flower clusters as late as June 1. The female 

 flower clusters, which may be from five to 

 twenty in number on a single tree, are not all 

 produced at the same time. It is necessary 

 in consequence to pollinate each flower clus- 

 ter as it appears, and sometimes an interval of several weeks elapses 

 between the appearance of the first and last flower clusters, so the 

 trees must be ascended several times. The Arabs are very expert in 

 doing this work and seldom overlook a tree, even where the palms 

 are planted without any order; indeed, they rarely miss even a single 

 flower cluster. It requires some skill to climb a tall palm tree, as 



FIG. 2. Date flower cluster after 

 artificial pollination; a sprig of 

 male flowers has been inserted 

 among the female flowers and 

 tied fast with a palm-leaf fiber. 

 (One-third natural size.) From 

 negative by the author. 



