CXLIV.—THE HORSESHOE VETCH. 
Hippocrepis comosa Linne. 
T he Tribe Hedysare<£^ to which the Horseshoe Vetch, the Bird’s-foot {Otnithopus), 
and the Sainfoin {Onobrychis) belong, presents evidence in several points of 
structure, such as the pollination-mechanism and that for seed-dispersal, of being 
one of the most highly specialised divisions of the Leguminoste. Not only have its 
members honeyed flowers, with diadelphous stamens and a piston-mechanism, 
similar to that of Lotus, but their pods, instead of dehiscing lengthways, as do most 
of the Family, are either one-seeded and indehiscent or form a lomentum or fruit 
which has transverse partitions and breaks up by their means into one-seeded joints. 
While in this way sufficient seed is produced and it is thrown to some little 
distance, it is, perhaps, protected against premature germination, or rotting, for a 
somewhat longer period than seeds would be, if scattered naked upon the ground, 
as in other groups. 
The Tribe takes its name from the genus Hedysarum, to which the Sainfoin was 
formerly referred, and which was also known as Pelecinum or Hatchet Vetch from its 
fruit, which in some species resembles a Malay kris and breaks up into hatchet-shaped 
segments, TieXe/fu?, pelekus, being the Greek for an axe. Closely allied to Hedysarum 
is the remarkable Telegraph or Semaphore Plant (Desmodium gyrans De Candolle), 
which has a pinnately trefoil leaf, the lateral leaflets of which, during warm weather, 
keep up a series of movements in elliptical orbits throughout the day, and “ sleep ” 
at night. 
The genus Hippocrepis was so called by Linnaeus, from the Greek iTrTros, 
hippos, a horse, and Kpr^TrU, krepis, a shoe, with reference to the segments of the 
fruit, on the ground that the older name Ferrum equinum, with the same significance, 
was inadmissible because made up of two words. It comprises twelve species of 
low-growing herbaceous plants, mostly natives of the Mediterranean area ; but our 
one British form {Hippocrepis comosa Linne) extends into southern Scotland. They 
may be annuals or perennials ; and while our species undoubtedly presents at first 
sight considerable resemblance to the Bird’s-foot Trefoil {Lotus corniculatus Linn^) 
it can be at once distinguished by its pinnate leaves of several pairs of leaflets with a 
terminal one. This terminal leaflet and all the lateral ones are of the same size, 
and small, membranous, undivided stipules are generally present. As they are 
glabrous, the specific name comosa, which Linne adopted from Rivinus, and which 
generally means “ hairy,” is as inappropriate to our species as to any other, though 
botanists seem to have agreed to consider it as in this instance meaning “ tufted.” 
Though the yellow flowers are sometimes solitary, they are generally, as in 
H. comosa, in an axillary umbellate group borne aloft on a relatively rather long 
peduncle. The calyx is divided into five acute segments, the two posterior 
segments being less deeply divided from one another than are the rest. The petals 
