Chap. VIII. CLEISTOGAMIC FLOWERS. 399 



CHAPTER VIII. 



CLEISTOGAMIC FLOWEES. 



General character of cleistogamic flowers — List of the genera producing 

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

 description of the cleistogamic flowers in the several species, their 

 fertility compared with that of the perfect flowers — Oxalis acetosella 

 — O. sensitiva, three forms of cleistogamic flowers — Vandellia — 

 Ononis — Impatiens — Drosera — Miscellaneous observations on various 

 other cleistogamic plants — Anemophilous species producing cleisto- 

 gamic flowers — Leersia, perfect flowers rarely developed — Summary 

 and concluding remarks on the origin of cleistogamic 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 for- 

 merly gave rise to warm controversies about the sexu- 

 ality of plants. These closed flowers have been appro- 

 priately named cleistogamic by Dr. Kuhn.* They are 

 remarkable from their small size and from never open- 

 ing, so that they resemble buds; their petals are rudi- 

 mentary or quite aborted; their stamens are often re- 

 duced 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 



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



