310 CLEISTOGAMIC FLOWERS. Chap. VUI. 



CHAPTEE VIII. 



OliBISTOGAMIO FlOWBKS. 



General character of cleistogamic flowers — List of the genera producing 

 such flowers, and their distribution in the vegetable series — Viola, 

 description of the cleistogamio flowers in the several species, their 

 fertility compared with that of the perfect flowers — Oxalis 

 acetosella— O. sensitiva, three forms of cleistogamio flowers — Van- 

 dellia — Ononis — Impatiens — Drosera — Miscellaneous observations 

 on various other oleistogamic plants — Anemophilous species produ* 

 cing cleistogamio flowers — Leersia, perfect flowers rarely developed, 

 — Summary and concluding remarks on the origin of oleistogamic 

 flowers — The chief conclusions which may be drawn from the 

 observations in this volume. 



It was known even before the time of Linnaeus that 

 certain plants produced two kinds of flowers, ordi- 

 nary open, and minute closed ones; and this fact 

 formerly gave rise to warm controversies about the 

 sexuality of plants. These closed flowers have been 

 appropriately named cleistogamio by Dr. Kuhn.* 

 They are remarkable from their small size and from 

 never opening, so that they resemble buds ; their petals 

 are rudimentary or quite aborted; their stamens are 

 often reduced in number, with the anthers of very 

 small size, containing few pollen-grains, which have 

 remarkably thin transparent coats, and generally emit 

 their tubes whilst still enclosed within the anther- 

 cells ; and, lastly, the pistil is much reduced in size, 

 with the stigma in some cases hardly at all developed. 

 These flowers do not secrete nectar or emit any odour ; 

 from their small size, as well as from the corolla being 

 rudimentary, they are singularly inconspicuous. Con- 



* 'Bot. Zeitung,' 1867, p. 65. 



