E UPHORBIA OE^. 159 



of vegetation.^ The stems are sometimes herbaceous, sometimes 

 fnitesoent, upright or climbing, volubile, sometimes arborescent, and 

 even occasionally attaining considerable dimensions. Sometimes 

 the axes, as in Xylophylla^ are flattened in cladodes, and sometimes, 

 as in certain species of Euphorbia and Pedilanthus^ they become 

 fleshy and cactiform. The leaves are usually alternate, rarely opposite 

 or verticillate, often provided with stipules, and even with stipels, 

 pretty often unsymmetrical at the base.^ The branches, leaves, 

 and stipules, may be changed into spines. The existence of glands 

 is very frequent in these plants, above all on the leaves and bracts, 

 or else occupying tolerably often the lateral place of the stipules, 

 and in the flowers, where they sometimes form highly developed 

 disks. Hairs are very common in this family, simple, glandular, 

 stellate, peltate, or squamate, occasionally compound ; ^ they are 

 sometimes even in the interior of the ovary cells. But that which, 

 at aU times, has been the most noticed amongst the general characters 

 of these plants, is the existence of a peculiar milky sap. In truth, 

 this point has been singularly exaggerated, for the latex is scarcely 

 observed with this quality in half the species of the family. But 

 the reservoirs of the latex often present in these a particular organi- 

 sation.* They form tubes, usually long, ramified, and spreading abun- 

 dantly throughout the parenchyma of the fundamental tissue. The 

 partitions are generally thick, and often to such a degree that the 

 transverse section resembles that of the fibres of the liber, with 

 which it has even been many times totally assimilated. It is 

 moreover in the neighbourhood of the liber bundles that they are 

 most developed, taking their places in certain cases. The branches, 

 very numerous in general, are directed inwards and outwards, some- 

 times completely transverse, towards the pith on one part, on the 

 other through the bark, arriving even, in certain species, close to 

 the surface of the stem, very numerous and very ramified, above all, 

 towards the insertion of the leaves. In some, these are true ducts ; 

 in others,^ they are only large ramified cellules, belonging essentially 



1 This question Is also treated witt details in with glandular apex, foliaceous lohes, or stipules 

 the Mt. Gen. Euphorbiae. 209-241. whose parenchyma is not developed, hut takes 



2 Usually (hut not constantly) the side of the all its growth abnormally in certain cirouni- 

 leaf which is most enlarged at its base, is that stances, and explains in this manner the true 

 which is found between the medial nerve and meaning of these organs. 



the branch (H. Bn. Etiphorbiac. 221), whilst in * Tbjeoul, ia Compt. Mend. Acad. So. Ixi. 1849 ; 



the Ur'icaeete, for example, the opposite has in Adansonia, vii. 169. 



been observed (Wedd. Monogr, Urtic. 12). * G. David, Ueb, die MilchuU. d. Euphorb. 



' These false compound, ramified, and glandu- Breslau (1872). 

 lar hairs are generally the nerves of the leaves. 



