and Cypripedioideae, no pollinia are formed; the anthers 
contain single pollen grains either dry or embedded in a 
viscid secretion respectively. 
ENpDOMORPHIC AND EXOMORPHIC FEATURES 
Vascularization. The distribution of vascular bundles 
in the stem and inflorescence-axis of orchids exhibits the 
same more or less scattered arrangement as is generally 
observable in the vegetative axis of other Monocotyle- 
dons. The bundles are enclosed within a sclerenchyma- 
like ring of perivascular fibers, either in a circular manner 
(similar to the primitive A7istolochia type in Dicotyle- 
dons) or in ascattered pattern. A preliminary investiga- 
tion indicates that the circular pattern is always associated 
with other primitive characters. Those species which ex- 
hibit this characteristic have a more or less well developed 
horizontal rhizome (e.g. A postasia, Cypripedium, Zeux- 
ine, etc.). Nevertheless, more information is needed be- 
fore the significance of this association may be fully and 
definitely evaluated. 
In the vascular supply of the flower, the bundles which 
enter the floral axis vary in number, and this variation is 
correlated with the primitive or advanced stage of the 
group. Swamy reports the number of vascular bundles 
in the Cypripedioideae as six; in the Neottiordeae and 
Ophrydoideae and the less specialized members of the 
Kerosphaeroideae three; while in the advanced types of 
the Kerosphaeroideae there is a further reduction in num- 
ber to two. Our investigation of the Apostasiordeae re- 
veals six vascular bundles, as is the case in the Cypriped- 
toideae. 
In A postasioideae and Cypripedioideae, the six bundles 
constitute the main traces of the ovary without further 
differentiation. In both of these groups, there is an ad- 
ditional seventh bundle which gives rise to the midrib 
of the bract. 
[ 64 | 
