spermae (Pl. XI, A). At maturity the cells of the outer- 
most layer of the integument lose their protoplast, and 
the seed coat becomes transparent. This type of seed is 
observable in every genus of the family, except in A pos- 
tasia, Adactylus, Selenipedium and Vanilla (Pl. X1, B). 
In these four genera, all layers of the outer integument 
and most of the inner integument enter into the formation 
of the seed coat which tightly surrounds the embryo; the 
testa becomes highly sclerotic, opaque and sculptured. 
It is rather remarkable that the presence of a primitive 
type of seed in Apostasioideae, Cypripedioideae and 
Neottioideae corresponds to the respective status of these 
groups.’ 
Gynostemium. One of the most distinct features of the 
Orchidaceae is the fusion of the stamens and style into a 
central organ, the column. This structure has generally 
been interpreted as an extension of the floral axis, thus 
being axial in origin. Recent studies, however, have 
shown it to be only an appendicular structure, since the 
morphological apex of the flower does not extend to the 
apex of the gynostemium, but only to the level of inser- 
tion of the perianth; the ovary contains all traces of the 
floral whorls and the gynostemium of the reproductive 
whorls. 
Even today there is a constant debate about the mean- 
ing and application of the terms ‘‘column”’ or ‘‘gyno- 
stemium.’’ The group 4 postasioideae, from time to time, 
has been kept apart from the Orchidaceae as a distinct 
1 It is noteworthy that, in addition to Vanilla, both Selenipedium and 
Apostasia possess aromatic substances. Epistephium and Galeola (Plate 
XI, A) of Neottioideae have also been reported to have essential oils in 
the fruits, but in lesser quantity. Kpistephium and Galeola have the 
seeds provided with a prominent, transparent wing (probably a dis- 
persal mechanism), but the embryo itself is enclosed by a sclerotic 
testa. Vanilla, Epistephium and Galeola p. pt. have been recognized as 
constituting a distinct family, Vanillaceae, on account of the charac- 
[ 70 | 
teristics mentioned above. 
