SEEDLING STRUCTURE IN THE LEGUMINOS. 11 
uniform type of structure, the transition being best described as “ inter- 
mediate-low.” The level of the transition, so far as different species can be 
compared in this respect, thus follows roughly the diameter of the seedling ;. 
the large seedlings having low, the small seedlings high, transitions, and 
those of intermediate size ranging between these extremes. Special mention 
should be made of Petalostylis labicheoides and Labicheu lanceolata ; here the 
distension of the base of the hypocotyl has no distinct influence upon the 
level of transition, which is of the type appropriate to much slenderer- 
seedlings. The stele in these cases remains narrow relatively to the breadth, 
of the whole section, and the structure conforms with what would be. 
expected if the whole hypocotyl had approximately the diameter of the- 
upper part. 
The primary xylem of the root in most cases is exclusively cotyledonary. 
In Bauhinia racemosa, however, the intercotyledonary plumular bundles may 
play a part in the construction of the root. Ceæsalpinia sepiaria is peculiar 
in that two of the root protoxylems are plumular and two cotyledonary ; tho: 
former show a persistence of mesarchy and a double structure for some 
distance up the first epicotyledonary internode. 
PAPILION AT. 
In this, the largest sub-order of the Leguminose, we find an immense 
amount of variety in every detail of form and structure. The mature plant 
may be a tree, shrub, liane, switch-plant, annual or perennial herb of erect, 
prostrate, or climbing habit. The seed varies widely in size, but is almost 
always devoid of endosperm. The embryo is usually curved, the radicle 
being accumbent ; but in Cicer, Arachis, Voandzeia, and some Dalbergiew 
and Sophorez the radiele is very short and straight (Taubert, 1894, p. 185). 
In certain Hedysarez the cotyledons are long and twisted in the seed, but in 
most cases they are simply folded face to face. The pressure of the hilum 
and radicle on the same edge makes them often more or less asymmetrical. 
Germination in some tribes is usually epigeal, a tendency -to become 
hypogeal being occasionally shown ; but the Viciex and Sophoree are 
almost entirely hypogeal, and this mode of germination is also frequent in 
the Phaseolez and Dalbergiew. The size of the seedling varies within wide 
limits, the volume of the hypocotyl of Canavalia ensiformis, for instance, being 
about seventy times that of Hippocrepis unisiliquosus. 
The seedling anatomy naturally reflects this manifold variety, though a 
certain uniformity is discernible throughout the sub-order. lt will be 
convenient to summarise the information aequired for the different tribes 
of Papilionatz separately ; for it often happens that a definite type of 
structure proves to be characteristic of a taxonomic group of species. 
