412 Remarks upon the Botanical Affinities o^Orobanche, 



system, must be considered nearly related members of the 

 same natural series. 



I am unwilling to dismiss this subject without adverting to 

 the placentation of Orobanchacece. That their capsule con- 

 sists of two carpels standing right and left of the axis of in- 

 florescence, and with the margins not inflected in the form of 

 dissepiments, is incontestable. Yet in Orobanche and Phely- 

 pa?a the capsule has four placentae, placed equidistant in pairs 

 upon the face of each valve or carpel, and considerably within 

 the margin. In Epiphegus each carpel has two intramarginal 

 placentas, which diverge from the base upwards, and terminate 

 before reaching the apex. In Lathrcea there is to each valve 

 but one placenta, which may be regarded as two confluent 

 ones occupying the very face of the dorsal suture of the car- 

 pel. And finally in JEginetia indica, and I believe in JEgi- 

 netia abbreviata also, the placenta is in like manner confined 

 to the axis of the valve, occupying the same position upon the 

 carpels as in Lathrcea, but broken up into a number of pa- 

 rallel plates of unequal depth, over the whole surface of which 

 multitudes of minute seeds are distributed. If we connect 

 these facts, about which there can be no sort of question, with 

 the well known placentation of Flacourtiacece, Nymphaacece, 

 and Butomacece, we shall find that they invalidate a general 

 carpological rule, that the placentas belong to the ventral su- 

 ture of a carpel, and consequently alternate with the dorsal ; 

 and we shall have to admit that the position of the placentas 

 with regard to the margins of the carpel is reducible to no 

 certain rule, but depends upon specific organization. Con- 

 sequently we shall no longer be unable to account for the un- 

 usual situation of the placentas opposite the stigma, in Papaver, 

 (as M. Kunth has lately noticed) in Parnassia, or elsewhere. 



We ought not indeed to be surprised at coming to this 

 result; for if the ovules are, as botanists generally believe 

 them to be, a modification of buds, then the uncertainty in 

 the position of the placentary lines will only be conformable 

 to the uncertainty in the origin of buds from leaves. If in 

 Bryophyllum, Malaxis paludosa, and most other cases they 

 usually spring from the edge of the leaf, they also arise from 

 its surface in ferns; and in the famous case of the Ornitho- 

 galum leaf mentioned by Turpin, they were found issuing in- 

 discriminately from all parts of its face. 



