| Mr. Brown, on the Proteaceae of Jussieu. | 35 |
Banksia dactyloides (the Conchium dactyloides of Dr. Smith), and which has equally escaped Cavanilles and Labillardiere in their characters of Hakea. Dr. Smith has more cautiously omitted this consideration in his character of that genus, and Professor Schrader has accurately described the suture as only existing on one side: such fruits then are as truly folliculi as those of Grevillea, Rhopala, or Embothrium; and that the existence of a distinct placenta is by no means necessary to constitute this kind of fruit, is proved even by some genera of Apocineæ, to which family this term was first applied.
A circumstance occurs in some species of Persoonia to which I have met with nothing similar in any other plant: the ovarium in this genus, whether it contains one or two ovula, has never more than one cell; but in several of the two-seeded species a cellular substance is after fœcundation interposed between the ovula; and this gradually indurating acquires in the ripe fruit the same consistence as the putamen itself, from whose substance it cannot be distinguished; and thus a fruit originally of one cell becomes bilocular: the cells however are not parallel, as in all those cases where they exist in the unimpregnated ovarium, but diverge more or less upwards.
In all the seeds of this order there is a very manifest chalaza, which, whatever may be the point of insertion of the seed, is always situated at the upper extremity; and I have not been able to observe any fasciculus of vessels connecting it with the umbilicus in cases where this latter is placed in a different part of the seed.
I am not aware of any function being ascribed to the chalaza of seeds, except the nutrition of their proper membrane: but it appears to me too remarkable a part to be destined for this purpose only; and some observations I have made induce
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