BOTANICAL SUBJECTS. 151 



verticillate leaves, in two whorls, the leaves of one alternating 

 with the leaves of the other. 



The accompanying diagram (Fig. 38) may give the reader a 

 better idea of what is meant : (a) represents each node of the 

 Thalidrum leaf, as would be seen from above, if the leaf were 

 erect, that is, three divisions of the petiole, with three alternating 

 scales ; (&) is a diagram of the leaf, with three alternating scales 

 at each node or division. 



In some species of Thalictrum these nodal scales have entirely 

 disappeared, so that the whole leaf looks like an ordinary decom- 

 pound leaf while in reality it is a branch pure and simple, functioning 

 as leaf. 



15. In many cases we find plants inheriting the leaves of 

 another order, only distantly allied to it, that is to say, of an order 

 not recognised by botanists as closely allied. For instance, in 

 JDendrohium Falcoji&i'i delicata, the leaves have an ochrasate vagina 

 and blade indistinguishable from the leaves of certain grasses, 

 although the latter are placed by systematists a long way off. Then 

 Dendrobes in their flowering stems have only ochr^eate vaginse, 

 without blades.* 



16. In other cases it would appear that an organ in one order 

 has been depauperized to the level of a homologous organ in 

 another order without their having had any proximate relationship, 

 other than that they descended from a common and more distant 

 centre. 



17. The fact is there appears to be in nature no such thing as 

 orders of plants. This term only means an artificial grouping of 

 individuals because they resemble each other in some of their 

 features. There is no law to prevent a leaf of one order, for 

 instance, growing like the leaf of another order, except the restraint 

 put on it by heredity, but this restraint may be frequently 

 interfered with by crossing, or by some other, at present unknown, 

 influence. It is enough to read through the order of SayindaccB, in 

 Lindley's " Yeg. Kingd.," to see how little resemblance there may be 

 in plants even of the same order. He says, '• This order is 

 composed of a great diversity of species, which assume appearances 

 widely different from each other ; so that botanists have not 

 unnaturally supposed that it really contains the elements of several 

 distinct natural orders. , . . The true character of soap worts 

 resides in their unsymmetrical flowers (the stamens never agreeing 

 in number or power with the sepals), in their anthers bursting 

 longitudinally, and in the petals having an appendage, while the 



* 



Such as we see in young bamboo stems, viz., vaginae, without blade or 

 with only an abortive blade. 



