191I3-] GOODSPEED: TRILLIUM SESSILE 19 



PISTILLODY OF THE PERIANTH IN TRILLIUM SESSILE. 



T. H. GOODSPEED. 



During the latter part of March, 1914, a considerable collection 

 of the familiar Trillium sessile, var. giganteum H. & A., was found 

 at the lower end of a small heavily shaded canyon in the Oakland 

 Hills. Approximately sixty plants were in flower and an equal num- 

 ber of plants bore no flowers, or flowers exceedingly rudimentary in 

 character. The mature flowers, with one exception, were all of them 

 normally developed, and varied in color from a light violet to deep 

 garnet. One plant, which in no way stood out from the rest by reason 

 of any unusual vegetative development, at once attracted attention 

 because of the abnormal flower which it bore. In this flower both co- 

 rolla and calyx were green and fleshy ; the color and texture of the 

 six perianth segments being that which is ordinarily characteristic 

 of the calyx of Trillium. These six similar segments were arranged in 

 two whorls of three parts each. The outer whorl, representing the 

 calyx, was characteristic in shape and size, while the inner whorl, 

 representing modified petals, corresponded in shape to the calyx seg- 

 ments, but were somewhat shorter. They also exhibited a peculiar 

 curling-in of their lower margins to form slender tubes, which ex- 

 tended for a distance of from 4 to 11 mm. up from their point of 

 attachment on the receptacle. When the curled edges were rolled 

 back the interior of the tubes that they formed were found to con- 

 tain a number of small greenish-white bodies attached near the 

 margins. The number was variable on the two curled edges of the 

 same segment, and one modified petal bore only three, which were 

 along one edge only. 



The color and general appearance of these protuberances on 

 the margins of the calyx-like petals suggested that they repre- 

 sented ovules. This supposition was to a certain extent confirmed by 

 the fact that the flower contained only a minute rudimentary pistil, 

 within which no structures resembling ovules were found. It is 

 almost the rule that Trillium sessile, var. giganteum in the San 

 Francisco Bay region produces no seed, or very little seed, but in the 

 normal open flowers the ovary will uniformly show maturing ovules 

 or unmistakable traces of them. (Fig. 6.) 



The attached photograph was made two days after the abnormal 

 flower had been collected, and in consequence the flower parts are 

 somewhat withered. Three of the ovule-like bodies are discernible 

 along the folded-back margin of one of the modified petals. By 

 reason of their greenish-white color, they stood out very strikingly 

 in the flower against the dark-green background. As can be seen, the 

 stamens, normally pollen-bearing apparently, are present. The 

 stamens were in no way abnormal. 



