40 University of California Puhlications in Botany [Vol. 7 



studies in this series (Gocxlspeed and Brandt, 1916, a and h) were 

 concerned witli a general description of tlie Californian species of 

 Trillium, with <i hi-icf inciilioii of cci-liiin points in their lifc-liistory 

 and a discussion of the origin, nature and significance of the widely 

 occurring undeveloped type of flower. The present paper, the third 

 in the series, is particularly concerned with the condition in which 

 these western species pass their resting period, a period apparently 

 determined by available moisture. The matter seemed of special value 

 since information is furnislied by the literature concerning the con- 

 dition of eastern species during a corresponding dormant period in 

 which both moisture and temperature relations ai"e seemingly con- 

 cerned. 



Chamberlain (1898) reports that spring-flowering perennial plants 

 either pass the wdnter in the spore mother-cell stage or mature their 

 spores before the winter season, but with the data at hand was unable 

 to decide which was the more general condition (cf. PfeifYer, 1912). 

 Among those plants which pass the winter in the spore mother-cell 

 stage he includes Trillium species, on the basis of the report of Miss 

 A. M. Smith (1896), who found that the pollen mother-cells were "in 

 the early stages of division" in a specimen dug from beneath the 

 frozen soil on April 5. She found the "later stages of division" and 

 pollen fully matured on April 15, when numerous plants were ap- 

 pearing above ground (cf. Gates, 1908, p. 46). Atkinson (1899), 

 working on T. grandiflorum (Michx.) Salisb. in the vicinity of Ithaca, 

 New York, where Smith had previously worked, reports that in all 

 plants he examined the pollen mother-cells were formed by the be- 

 ginning of winter, and that in open woods on rather high ground, 

 protected from north and west winds, pollen was often mature in 

 September. In cold ravines, on the other hand, plants entered into 

 the resting period in the pollen mother-cell stage. Late in February 

 and early in ]\Iarch, when the w^eather is relatively warm, formation 

 of pollen begins. The report of Ernst (1902) dealing with the con- 

 dition of Paris quadrifolia L. and Trillium grandiflorum tends to con- 

 firm that of Smith, noted above. He states that micro- and megaspore 

 mother-cells become plainly distinguishable toward the beginning of 

 the growing season, late in February or early in IMarch. Chamberlain 

 (1898) also reports four potential magaspores fully formed in April 

 on a plant of T. recurvatum Beck, not more than 5 cm. high. The 

 above reports show that Trillium species native in the Eastern United 

 States and cultivated in gardens in Northern Germany usually mature 



