2G6 OBSERVATIONS ON THE NATURAL FAMILY
unites with it considerably below its termination. In H. tenuifolim this irregularity is still greater ; one branch being not unfrequently altogether wanting, and even the re- maining branch considerably weakened : where this happens a secondary vessel is always produced, though very few flosculi are furnished with five complete middle nerves.
To the fact stated by M. Cassini that the lateral nerves are always simple, I have met with only one apparent exception, in an unpublished species of Madia, where they are connected by a few branches with the secondary or B4] middle nerve, which in this plant is more strongly marked than the primary, and from which indeed these connecting branches probably originate.
It must, I think, be admitted by M. Cassini, that in many genera of Compositae five vessels passing through the axes of the segments exist, even ten others are occa- sionally found, as in Helianthus, though these can hardly be traced below the insertion of stamina. But as it has been already shown that the lateral or primary vessels are not strictly marginal through their whole length, and as one instance has been produced in which their branches, if not themselves subdivided, are at least connected by ramifica- tions of the middle nerves, 1 it follows that a monopeta- lous corolla having in its tube fifteen nerves with distinct origins, three of which are continued through each of its segments, and unite together at the apex, would upon the Avhole better correspond with the definition M. Cassini has given of the Corolla of Compositae, than the actual dispo- sition of vessels in that order. Now such a structure exists in the whole of Goodenovise, 2 a family of plants very
1 M. Cassini himself (in a note to his third memoir published in the Journal de Physique for February 1816, p. 129) has given another instance of the rami- fication of nerves in ha frutescens.
2 I have formerly observed (in Prodr. Flor. Nov. Holl. p. 580, and in General Remarks on the Botany of Terra Australis [vol. i,p. 33]) that Euthales and Velleia, genera belonging to Goodenovite, exhibit the remarkable and nearly peculiar character of a corolla having the lower part of the tube cohering with the ovarium, while the calyx is entirely distinct. I have at the same time remarked that, even in those genera of the same natural famiiy in which the calyx is coherent, the tube of the corolla may be supposed to be continued down to the base of the ovarium ; and that this becomes even evident in such species as have the
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