322 THE VEGETABLE WORLD. 
resembling those of Menisperms. This class Dr. Lindley con- — 
siders to be distinct from LEndogens on the one hand, and 
Exogens on the other. He calls them Dictyogens, from the netted 
structure of their foliage. They are distinguished as having 
leaves net-veined, deciduous ; wood of the stem, when perennial, 
arranged in a circle round the central pith, the wood of the root 
being exogenous, that is, without concentric circles, and the leaves 
falling off the stem by a clean separation, as in Exogens. 
Flowers bisexual, with adhering perianth, carpels consolidated, and ) LXVI. Dioscoreacez. 
several seeded, including the Yam of tropical countries. s 
Flowers hexaperdal, bisexual, carpels several, placenta axial, including } LXVII. Smilacez. 
the diuretic Sarsaparilla of South America. 
Flowers three, six-petaloid, unisexual, carpels several, placenta perietal. LXVUI. Payee 
Flowers tripetalous, bisexual, carpels several, axial placenta... » LXXI. Trill 
Flowers bisexual, carpels solitary, simple, many-seeded, and basal i LXXII, Roxburghiace®- 
placenta, 
” 
“ 
The DicrrocEenex, from 8:crooa, “a net,” and yweobat, - be, 
ivisi : _ e one 
are a small division of plants, partaking of Endogens on t 
hand, and Exogens on the other. The foliage is broad, eee - 
veined, and branching; but simple, and of regular outline ; 2 
leaves disarticulating with the stem, and in some cases the om 
green flowers are very nearly the same as some of the oP 
mum among Exogens. “For these reasons,” says Dr. Lindley, 
genus” (of sarsaparilla), he adds, “the wood is di 
of the cylinder having an evident tendency to arrange t oe 
in lines forming rays from the centre.” 
: : -. dimcious HOWSr 
The Droscorzacex are distinguished by their diccious: ae 
superior calyx and corolla, six stamens and 7 
They are all twining shrubs. The various species © : 
and Testudinaria produce edible farinaceous tubers, bui 
exhibits a dangerous acridity. - 
In the order Dioscoreacee we find the tropical , | 
Yams, a genus of fleshy-rooted diccious plants, wit © i 
twining stems, broad alternate leaves with netted 3 
Thamus 
: 
«ty 
have endeavoured to show that they ought to be — wes 
transition class, partaking somewhat of the nature of En Bae . 
and also of that of Exogens. In the rhizome of the" ante. 
ae in a com- 
‘ true 
pact circle, below a cortical integument, and smi fois | 
pith ; in Smilax aspera the woody matter is disposed are er 
of a cylinder, enclosing a centre of soft cellular matter, the ve ine 
