TR0TEACE2E. 403 



tracheae of the medullary sheath ; the existence of sclerous cells 

 disseminated in masses through the pith, and even in the medullary 

 rays and cortical parenchyma. These peculiarities, well worth 

 particular study, are rarely found united in a single plant, as occurs 

 in certain cultivated species of the genus Stenocarpus. 



But the leaves are the vegetative organs to which most attention 

 has been devoted by botanists and palaeontologists. They never 

 possess stipules. They are almost always alternate, though some- 

 times opposite, as in Xylomelum, or verticillate, as in several species 

 of Andripetalum. 1 The blade is usually thick, coriaceous, and dry, 

 sometimes flattened, sometimes rounded or cylindrical. It is pretty 

 frequently entire, still oftener incised in some way or other ; some- 

 times toothed, sometimes pinnatifid or pinnatisect. It may be 

 simply bilobed, with equal or unequal lobes and an empty sinus 

 between them ; or there may project into the sinus (as in Dilobeia) 

 a gland representing the modified end of the midrib. Finally, in 

 some genera the leaves are quite pinnate, 2 or one may find both 

 simple and compound leaves on one and the same branch ; for in 

 this order we often find these organs polymorphous on the same 

 plant or branch. In a given species, then, we may find some leaves 

 simple, and others much divided, recalling those of a Leguminose, 

 Araliad, or even Umbellifer. The apex of the leaf is often mucro- 

 nate or spinescent ; the upper surface is usually smooth and gla- 

 brous, while the lower is often covered with a whitish or brownish 

 down. The form of the leaves and the condition of their surfaces 

 result in a peculiar distribution of the stomates, 3 which here possess 



1 This character does not appear constant in 3 This distrihution depends mainly on the 



this genus; it is, however, one reason for think- form of the blade. Where it is flat and mem- 



ing that certain Oceanian Ilelicias should be branous, the stomates are confined to the lower 



referred to Andripetalum. Hence, perhaps, it face, as in Ayastachys, Cenarrlienes, Lambertia, 



is to the latter rather than the former genus Symphyonema, Stenocarpus, Lomatia, Banksia, 



that we should refer the genus Cylindria of and Dryundra, as well as in many species of 



Loureiko (Ft. Cock., ed. Vlyssip., 1790, 69), GreriUea. But several species of this genus 



which has opposite leaves, 4-merous flowers, and a have stomates above as well as below. In the 



double perianth (?), to the inferior divisions of flat-leaved species of Orites they are only found 



which are superposed the stamens. This genus below ; but where the leaves are cylindrical 



was attributed by Kcenig (in Ann. of Bot., i. they are all over them. This last is the case in 



392) to Oleinecp ; but perhaps, thinks II. Brown the leaves of Halea, Petrophila, Conospermum, 



(in Trans. Linn. Sue, x. 224), this is through Franklandia, StirHngia, I>< ll< ndena ; but the 



some confusion. It does not appear to us im- blade and its lobes are not always rounded or 



possible that Cylindria may, after all, belong to cylindrical, and the stomates are found on both 



Loranthacem or Olacacece ; for it differs from surfaces of the leaves of Persoonia and Synaph 



Eelicia in having a double perianth. which are often flattened. Protea has long I 



■ The divisions are not, however, usually sepa- cited for its poverty in stomates, though the 



rated by distinct articulations. blade is firm and coriaceous. 



L) 1) •- 1 



