SPECIAL FORMS. 



65 



126. Stems serving the purpose of foliage, Phyllocladia. Most 

 of these condensed and permanent stems are illustrations of 

 this, their green rind doing duty for leaves, which 

 are either absent, or transient, or reduced to 

 spines or other organs not effective as foliage. 

 In the flat and broad-jointed species of Opuntia, 

 and still more in Phyllocactus and Epiphyllum, the 

 forms assumed give a considerable surface of green 

 rind, which well answers the purpose of leaves. 

 Flattened stems or branches of the same sort and 

 economy not seldom occur in other than fleshy or 

 succulent plants (such as the Cactuses) ; some- 

 times accompanied by a certain number of real 

 foliage-leaves, but these more or less transient, 

 as in Bossisea and Carrnichselia among Legu- 

 minous shrubs, and Muhlenbeckia platyclada, now 

 in common cultivation (Fig. 121) ; sometimes 

 with all the leaves reduced to small and function- 

 less scales, as in the Xylophylla (i. e. wooden- 

 leaved) section of Phyllanthus, and in Phyllo- 

 cladus (New Zealand and Tasmanian trees of 

 the Yew family) . In all these, the cauliue nature 

 is manifest by the continuous or proliferous 

 growth, by the marked nodes and internodes, 

 and often by the bearing of flowers. 



121 



127. Cladophylla (literally, branch-leaves) are more ambigu- 

 ous in character. The most familiar examples are found in the 

 peculiar foliage of Ruscus, Myrsiphyllum, Asparagus, and in 

 some other genera of the same family. In these the primary or 

 proper leaves of the shoots are little scales, one to each node, and 

 quite functionless. From the axil of each is immediately pro- 

 duced a body answering in all respects to the blade of a leaf, 

 both in appearance and in office. They also accord with leaves 

 in being expanded horizontally, although they take a twist which 

 brings them more or less into a vertical position, in the manner 

 of phyllodia (that is, of leaf-stalks assuming the form and office 

 of leaf-blades, 217) ; wherefore they ma} 1 be regarded as the 

 first and only leaf of an axillary branch with the internode 

 under the leaf wholly undeveloped and no further growth ever 

 taking place. But, on the other hand, their anatomical structure 

 is said to be that of sterns rather than of leaves. Moreover, 



FIG. 121. Foliiform branch of Muhlenbeckia platyclada, growing from the apex, 

 bearing a small and transient leaf at some nodes, also a flower or two. 



