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Show 332 OLEISTOGAMIC FLOWERS. CHAP. VIII. d the gardener detected that they were the prodilCt ~~ minute bud-like bodies, three or four of. which conld someti1nes be found on the sa1ne umbel w1 th the perfect flowers. They were quite closed and hardly thicker than their peduncles. The sepals presen~ed nothing particular, but internally and alternating 'th then1 there were five small flattened heart-shaped WaI pillrn, li'k e rudiments of petals; but t }1 e h omo l og1. eal ~ature of which appeared doubtful to Mr. Bentham and Dr. Hooker. No trace of anthers or of stan1ens could be detected ; and I knew from having examined many cleistogamic :flowers what to _look for. Thm:e were two ovaries, full of ovules, quite open at. theu upper ends, ,\rith their edges festooned, but w1th no trace of a proper stigma. In all these flowers one of the two ovaries withered and blackened long before the other. The one perfect capsule, 3! inches in length, which was sent me, ·had lik_ewise been developed from a single carpel. This capsule c?ntained an abundance of plumose seeds, many of ~hwh appeared quite sound, but they did not germ1n~te when sown at Kew. Therefore the little bud-hlm flower which produced this capsule probably was as destitute of pollen as were those which I exa1nined .. Juncus bufonius and. HordeU'm.-All th~ speCI:s hitherto mentioned which produce cle1stogamw flowers are entomophilous ; but four genera, J u11cu~, Hordeum, Cryptostachys, and Leersia are ane~op~llous. Juncus bufonius is remarkable* by be~nng 111 parts of Russia only cleisto~amic flowers, whw~ contain three instead of the SIX anthers found 111 the perfect flowers. In the genus Hordeum it has been * See Dr. Ascherson's m. terest·m g paper m· ' Bot · Zeitung ' ' ISil, p. 551. CHAP. VIII. LEERSIA. 333 shown by Delpino* that the majority of the fl wers are cleistogamic, some of the others expand.ino- and apparently allowing of cross-fertilisation. I hear from Fritz Muller that there is a grass in Southern Brazil, in which the sheath of the uppermost leaf, half a metre in length, envelopes the whole panicle; and this sheath never opens until the self-fertilised seeds are ripe. On the roadside some plants had been ·ut down, whilst the cleistogamic panicles were developing, and these plants afterwards produced free or unenclosed panicles of small size, bearing perfect flowers. Leersia oryzoides.-It has long been known that this plant produces cleistogamic·flowers, but these were first described with care by M. Duval-Jouve.t I procured plants from a stream near Reigate, and cultivated them for several years in my green-house. The cleistogamic flowers are very small, and usually mature their seeds within the sheaths of the leaves. These flowers are said by Duval-J ouve to be filled by slightly viscid fluid; but this was not the case with several that I opened; but there was a thin film of fluid between the coats of the glumes, and when these were pressed the fluid moved about, giving a singularly deceptive appearance of the whole inside of the flower being thus filled. The stigma is very small and the filaments extremely short; the anthers are less than io of an inch in length, or about one-third of the length of those in the perfect flowers. One of the three anthers dehisces before the two others. Can this have any relation wi~h the fact that in some other * ' Bollettini del Comizio agrario Parmense.' Marzo e Aprile, 1R7l. An abstract of this valuable paper is given in 'Bot. Zeitung,' 1871, p. 537. See also Hildebrand on Hordeum, in 'Monatsbericht d. K. Akad. Berlin,' Oct. 1872, p. 760. t ' Bull. Bot. Soc. de France,' tom. x. 1863, p. 194. |
