I 



311 

 ON THE POLLINATION OF YUCCA WHIPPLEI IN CALIFORNIA. 



By D. W. ('(X^uiLLK'n, Ao.v Amjclex, Cal. 



In Yueea ivhipplei all of the leaves are borne next the gronnd, and 

 the flower- stalk, which sometimes attains a height of twelve feet, is naked 

 except for the small, scarious bracts. The flowers are in a dense pan- 

 icle, and are borne on the upper third of the flower-stalk. The flowers 

 are pendulous, and of a pure waxy whiteness within, the outside being 

 more or less tinged with green; the form is rotate- spreading, or some- 

 what saucer-shaped. Tlie stamens are as long as, or slightly longer 

 than, the deeply-lobed ovary, including the short, conical style and large 

 stigma. The latter is hairy-papillose, and is of a deep green color, con- 

 trasting strongly with, the pure whiteness of the other parts of the 

 flower. The stamens are almost as spreading as the periantli, and 

 each one is surmounted by a pair of i)ollen-masses inclosed in thin mem- 

 brane, which finally si)lits in two and falls away, leaving the viscid 

 pollen-masses still adhering to the top of the stamen. After pollination 

 has taken place the ovary increases in size, the perianth and stamens 

 wither and finally fall away, and as the ovary or seed-pod continues to 

 grow it gradually turns around, so that from its pendulous position it 

 finally becomes upright, and remains in this position until ripe, after 

 which it splits open, allowing the seeds to escape. This Yucca has 

 about the same distribution in California as haccata, but to the eastward 

 it extends only as far as Arizona. The California Indians feed upon the 

 juice of the young plants, and also roast them for food. With this 

 species, unlike the two other kinds mentioned above, the entire i)lant 

 dies after flowering, although before this takes place one or more young 

 plants usually start out from the base of the old one. The flowering 

 season usually extends from about the first of May to the middle ot 

 August. 



As Dr. Riley, has shown, the Tineid moths, Pronuba maculata and 

 Frodoxus piUverulentus, live in the larva state, the former in the seeds 

 and the latter in the seed-pods ; while Frodoxus marginatus, F, cinereus, 

 and P. wnescens^ live in the flower-stalks and petioles of Yucca ivMiyplcL 

 There are six other kinds of insects Avhich I have observed to live at the 

 exi:)ense of this plant. The largest of these is a showy red and black 

 Oerambycid beetle, Tragidion a7i)iatum,ihe larvtie of which live in the 

 dead and dry flower-stalks; the beetle is quite rare, but is occasionally 

 met with in mid-summer, resting upon the green flower-stalk in the 

 daytime. The largest weevil known to me to occur in California feeds 

 upon the green flower-stalks of this Yucca, usuall}^ taking up its posi- 

 tion low down upon the jflant, where it is more or less hidden from view 

 by the leaves; this is the Scyphophorus yucccc. A much smaller weevil, 

 t\iQ> Macrorhyncolus protr actus ^ lives in the dry flower-stalks. The three 

 remaining insects referred to belong to the Hemiptera, and I have thus 



