84 MR. R. H. COMPTON : AN INVESTIGATION OF THE 
The germination is almost always epigeal ; De Candolle (1825) among 37 
species recorded no exception to this rule; but Arachis hypogwa is apparently 
very near to being hypogeal, for though the cotyledons usually appear above 
ground, they are very thick and fleshy, do not expand, and never turn green ; 
Lubbock (1892, p. 392) mentions that “ ће cotyledons of Lespedeza juncea 
are subterranean, or if they rise above ground they perish early.” According 
to Lubbock, the cotyledons of Lespedeza are densely pubescent (cf. Ononis 
biflora). There is much variety in the form of the cotyledons, the two main 
types being the ovate and the linear; the latter is found in Scorpiurus 
and Hippocrepis, the former in most other genera. The cotyledons of 
Scorpiurus vermiculatus may reach 10 em. in length, but remain uniformly 
narrow and contain throughout a median and two lateral bundles. A 
cotyledonary tube is frequently present, being especially well-marked in 
Hedysarum coronarium ; it is often closed for a greater distance on one side 
than on the other. Where the first leaves are alternate the cotyledons are more 
or less secund, being. turned away from the side on which the first leaf 
appears ; the cotyledons have often a straighter edge on this side than on the 
other, owing to the incumbent folding of the radiele against this edge in the 
seed and to the pressure of the hilum. Arachis hypogwa is one of the few 
Papilionatz with a straight embryo. 
The root may exhibit tetrarchy or triarchy, both conditions being common, 
and sometimes found within the limits of a genus.  Diarchy is recorded 
for the single example of the sub-tribe Patagoniin:e examined, viz. Adesmia 
(Van Tieghem and Douliot, 1888, p. 173) ; but has not been observed else- 
where. Triarchy seems to be characteristic of the sub-tribes Coronilline and 
Eu-Hedysarin:z, in which the first leaves are alternate, or else more than 
one stem is produced from the plumule ; but triarehy has not been found in 
the Desmodiine, in which the first two leaves are frequently opposite, 
tetrarchy being the general rule. Tetrarchy is also found in the roots of 
some Coronilline. This relation between the type of symmetry and the 
position of the first two leaves has been observed also in the Galegeæ, and 
appears to be a general principle (pp. 83, 103). 
When tetrarchy occurs in the root it persists throughout the hypocotyl, 
and each cotyledon takes a polar xylem and halves of the two lateral 
xylems, together with two of the phloems from the root. In some cases 
of triarehy each cotyledon takes one and a half root xylems, and one and 
a half root phloems. 
Between uniform tetrarchy and triarchy there is an interesting series 
of seedlings in which a fourth protoxylem is added to the triarch structure 
of the root. In Onobrychis Caput-galli the fourth xylem appears at the 
external collet. In Scorpiurus sulcata the same may happen, or in some cases 
tetrarchy is not attained till half-way up the hypocotyl. In Ornithopus 
compressus the fourth xylem appears in the upper part of the hypocotyl 
