350 PROCEEDINGS OF THE ACADEMY OF . [1880. 



to the lengthening of the stamens and the form of the corolla-tube 

 is the same in both sexual forms. The number of plants repre- 

 senting each sexual form is about equal. In a handful of plants 

 gathered at random there were of Houstonia serpyllifolia thirteen 

 with long styles and short stamens, and eleven with short styles and 

 the anthers in the mouth of the tube. Of Houstonia j)urpurea 

 there were thirteen with long styles to fourteen with short ones. 

 An interesting fact in connection with these sexual differences is 

 that the dimorphism seemed to be wholly in the shortening of the 

 style or filaments, and did not seem to effect injuriously the 

 anthers or stigma. Both forms seemed to be equally fertile. 



In answer to a question by Mr. Redfleld, Mr. Meehan said there 

 did not appear to be any intermediate forms. The stigma or the 

 anthers were either exactly at the throat of the flowers, or exactly 

 at the base. In regai'd to cross fertilization the long styled would 

 be in the best position for receiving pollen from foreign flowers, 

 but the short styled one would more readil}" receive its own. As 

 cross and self-fertilization had an equal advantage he would infer 

 that the dimorphism had little reference to fertilization as a final 

 cause. 



Gleistogam.y in Oxo.lis Acetosella, L. — Mr. Meehan observed 

 that under the forests of Abies Frazeri^ on Roan Mountain, North 

 Carolina, early in August Oxalis Acetosella was abundantly in 

 flower. 



In a large number of cases examined he could find no traces of 

 any disposition to produce seed vessels, but pushing out beneath 

 the soil or near the surfece were numbers of cleistogene flowers, 

 from which, in all probability, seeds would be produced in abun- 

 dance. 



Most plants which produced cleistogene flowers, also produced 

 the usual open corolla bearing flowers at one time or another in 

 the season, and it had been suggested that this bright petalled 

 condition was for the purpose of attracting insects, and thus give 

 the species some chance to escape from the evils which cleis- 

 togamy, or close-breeding is supposed to involve. It is worthy 

 of note that no day insects were noted to visit the flower of the 

 Oxalis blooming in these dark fir forests, though nocturnal ones 

 might supply tlie deficiency. Mr. Meehan remarked, however, 

 that no rule could be deduced from single observations, or obser- 

 vations repeated in the same localities, as the behavior of 

 plants and insects varied with circumstances. The Oxalis might 

 not be cleistogene, might be visited by insects, and the open 

 flowers mioht be fertile elsewhere. He referred in illustration to 

 Amphicarpsea monoica^ Nutt., which near Philadelphia sometimes 

 produced no seeds from the petaliferous flowers, while at other 

 times these flowers were remarkably fertile. Again, all his exam- 

 inations in the locality named had resulted in finding that the 



