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 196 ON THE ASCLEPIADEiE.

a character at once obvious and important, and which while it preserves the natural series unbroken, has the additional advantage of dividing the order into two nearly equal parts. To one of these which includes the genus Apocynum, the name of Apocineae will of course remain.

The consideration of the other, which from one of its most remarkable genera I propose naming AsclepiadejE, forms the chief subject of the following essay; but the more completely to illustrate it, I have subjoined new, and I trust amended characters of the genera of the most nearly related section of the Apocinese strictly so called. The u] singular structure of the stamina in the Asclepiadese has attracted the attention of botanists since the days of Tournefort : it is therefore not a little remarkable, that two opposite opinions should still be held even respecting the origin of these parts, and that between these opinions bota- nists should be almost equally divided.

In a paper w 7 hich was some time ago read to the Linnean Society of London, 1 1 had occasion, in inculcating the neces- sity of examining the parts of the flower before expansion, to advert to this tribe of plants ; and I there entered at some length, both into the opinions generally received re- specting their male organs, and also into that which I had deduced from an examination of these parts before the opening of the corolla : and being unwilling to repeat now, what I then stated, I shall content myself with referring to the figures and descriptions published by Jacquin in the first volume of his " Miscellanea Austriaca," which give a correct idea of the state of the organs after expansion ; and only add the observations I have made on one species of the family, the Asclepias Syriaca, in the earlier stages of the flower.

The flower-bud of this plant I first examined, while the unexpanded corolla was yet green and considerably shorter than the calyx. At this period, the gland-like bodies which afterwards occupy the angles of the stigma were absolutely invisible ; the furrows of its angles were ex-

1 [Ante, pp. G— 8.]

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