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Show 318 CLEISTOGAMIO FLOWERS. CHAP. VIII. lated development : I found on a purple variety, after it had produced its perfect double flowers, and whilst the white single variety was bearing its cleist10- gamic flowers, many bud-like bodies which from their position on the plant were certainly of a cleistogamic nature. They consisted, as could be seen on bisectin()' . b them, of a dense mass of minute scales closely folded over one another, exactly like a cabbage-head in miniature. I could not detect any stamens, and in the place of the ovarium there was a little central column. The doubleness of the perfect flowers had thus spread to the cleistogamic ones, which therefore were rendered quite sterile. Viola hirta.-The five sta1nens of the cleistogamic flowers are provided, as in the last case, with small anthers, from all of which pollen-tubes proceed to the stigma. The petals are not quite so much reduced as in V. canina, and the short pistil instead of being hooked is merely bent into a rectangle. Of several perfect flowers which I saw visited by hive- and humblebees, six were marked, but they produced only two capsules, some of the others having been accidentally injured. M. Monnier was therefore 1nistaken in this case as in that of V. odorata, in supposing that the perfect flowers always withered away and aborted. He states that the peduncles of the cleistogamic flowers curve downwards and bury the ovaries beneath the soil.* I may here add that Fritz Muller, as I hear from his brother, has found in the highlands of Southern Brazil a white-flowered species of violet which bears subterranean cleistogamic flowers. * These statements are taken from Profe::lsor Oliver's excellent article in the ' Nat. Hist. Review,' July 1862, p. 238. With respect to the supposed sterility of the perfect flowers in this .gen~s see also Timbal-Lagrave m Bot. Zeitung,' 1854, p. 772. CHAP. VIII. VIOLA. 319 Viola nana.-Mr. Scott sent me seeds of this Indian species from the Sikkim Terai, from which I raised many plants, and from these other seedlings during several successive generations. They produced an abundance of cleistogamic flowers during the whole of each summer, but never a perfect one. When Mr. Scott wrote to me his plants in Calcutta were behaving similarly, though his collector saw the species in flower in its native site. This case is valuable as showing that we ought not to infer, as has sometimes been done, that a species does not bear perfect flowers when growing naturally, because it produces only cleistogamic flowers under culture. The calyx of these flowers is sometimes formed of only three sepals; two being actually suppressed and not merely coherent with the ot~ers; this occ~rred with five out of thirty flowers whiCh were examined for this purpose. The petals are represented by extremely minute scales. Of the sta~ ens, two bear anthers which are in the same state as In the previous species, b~t, as far as I could judge, e.ach of the two cells contained only from 20 to 25 delicate ~ransparent pollen-grains. These emitted their tubes In the usual manner. The three other stamens bore very minute rudimentary anthers, one of which was genera~ly larger than the other two, but none of the~ contained any pollen. In one instance, however a Single c~Il of the larger rudimentary anther in~ ~luded a httle pollen. The style consists of a short attene~ tube, somewhat expanded at its upper end, and . this forms an open channel leadino- into the ovanum as des 'b d d V B b ' en e un er . canina. It is slightly ent. towards the two fertile anthers. h Vwla Roxburghiana.-This species bore in my hot fl ouse during two years a multitude of cleistoo-ami·c-owers wh' h b be. ' IC resem led In all respects those of the |
