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Show 326 CLEISTOGAMIC FLOWERS. CHAP. VIII. this is not the case, according to Von Mohl, with the cleistogainic flowers of other Leguin1nosm. Five of the stamens are destitute of anthers, and alternate with the :five thus provided. The two cells of the anthers are minute, rounded and separated fron1 one another by connective tissue; they contain but few pollengrains, and these have extremely delicate coats. The pistil is hook-shaped, with a plainly enlarged stigma, which is curled down, towards the anthers; it therefore differs much from that of the perfect flower. During the year 1867 no perfect flowers were produced, but in the following year there were both perfect and cleistogamic ones. Ononis minutissi1na.-My plants produced both perfect and cleistogamic flowers ; but I did not examine the latter. Some of the former were crossed with pollen from a distinct plant, and six capsules thus obtained yielded on an average 3 · 66 seeds, with a maximum of 5 in one. Twelve perfect flowers were marked and allowed to fertilise themselves spontaneously under a net, and they yielded eight capsules, containing on an average 2 · 38 seeds, with a maximum of 3 in one. Fifty-three capsules produced by the cleistogamic flowers contained on an average 4 ·I seeds, so that these were the most productive of all; and the seeds themselves looked :finer even than those from the crossed perfect flowers. According to Mr. Bentham 0. parviflora likewise bears cleist.ogamic flowers; and he inforn1s Ine that these flowers are produced by all three species early in the spring; whilst the perfect ones appear afterwards, and th~refore in a reversed order compared with those of Viola and Oxalis. Some of the species, for instance Ononis . columnfE, bear a fre~h crop of cleistogamic flowers in the autumn. L athyrus nissolia apparently offers a case of the first CHAP. VIII. IMPATIENS. 327 stage in the production of cleistoo·ainic flowers for on plants growing in a state of natur~, many of th~ flower never expand and yet produce fine pods. Some of the bu~s are so large that they seem on the point of expansion; others are much sinaller, but none so small as t?e true cleistogamic flowers of the foregoing species. As I marked these buds with thread and examined them daily, there could be no mistake about their produe · ng fruit without having expanded. S~veral other Leguminous genera produce cleistogamic flowers, as may be seen in the previous list; but much does not appear to be known about them. Von Mohl says that their p~tals are con1monly rudimentary, that only a few of theu anthers are developed, their filaments are not united into a tube and their pistils are hook-shaped. In three of the (Yenera namely Vicia A. h. 0 ' ' mp Icarpma, and Voandzeia, the cleistogamic flowers are produced on subterranean stems. The perfect fl~wers of Voandzeia, which is a cultivated plant, are said never to produce fruit;* but we should remember how often fertility is affected by cultivation. Impatiens fulva.-Mr. A.. W. Bennett has published an excellent description, with :figures, of this plant.t :S:e sh?ws that the cleistogamic and perfect flowers differ In structure at a very early period of growth so that the existence of the forn1er cannot be due me;ely to the arrested development of the latter -a conclusion wh~ch_ indeed follows from most of the previous descnptions. Mr. Be~nett found on the banks of the Wey that the plants wh1ch bore cleistogamic :flowers alone were to those bearing perfect flowers as 20 to 1; but .* Correa de Mello ('Journal Lmn. Soc. Bot.' vol. xi. 18 iO, p. 254) ~articula.rly attended to the flowermg and fruiting of this African plant, which is sometimes cultivated in Brazil. t 'Jourual Linn. Soc. Bot.' vol. xiii. 1872, p. 147. |