54 PROCEEDINGS OF THE ACADEMY OF [1889. 



some accident has bent in early stages to the ground. But a per- 

 fect illustration is seen in a variety known as the "Brush straw- 

 berry," which never makes any stolons or, as they are technically 

 called, " runners," because, as is readily seen, what should have 

 been runners in the usual varieties have become erect, and, with 

 erection, have changed their character to flower scapes. The leaves 

 are quite abundant among the flowers, and are on one side, as 

 they are on the thick stemmed Begonias, and as they would be on 

 a strawberry runner trailing on the ground. 



It is evident that under the conception of a continuous spiral ar- 

 rangement, the leaves, from a stem arranged for horizontal growth, 

 could not all spring from one side as in the Begonias and other 

 plants referred to ; nor is there any method conceivable except that 

 each leaf or bud in succession should be made to twist in contrary 

 directions. AVe can see that this is so in the thick flowering shoots 

 of the Yucca filamentosa, where the suppressed leaves, reduced to 

 mere bracts, show the alternate twisting from right to left, 

 and from left to right. (Fig. 1.) Examining the flowers 

 on the branchlets of the panicle, we see that they also al- 

 ternately twist in opposite directions, and that they are 

 secund. In fact, the flower scape of this Yucca is but a 

 rhizoma, forced to assume an erect position, changed in 

 many of its characters by that unknown law which comes 

 in a highly accelerated growth, and results in changing 

 Fig. i. leaves and stem into inflorescence, although not wholly 

 affecting the unilateral character that prevailed in its horizontal 

 condition. 



If we examine any cases of secund inflorescence, we may in most 

 instances see that this condition arises from the alternate twisting 

 of the pedicels in contrary directions. 



So far as the author can now recall, the secund inflorescence, aside 

 from that classed as scorpioid, does not exist among annuals, and we 

 may assume that it is rare in that class. In perennial herbaceous 

 plants it is common. Conceding that, as a general law, plants in 

 time come to adapt themselves to the best conditions of existence, 

 and that as a general law it would be better for leaves and flowers 

 to be scattered equally around an axis than to be crowded on one 

 side, the conclusion is rationally reached that a secund inflorescence 



