ANGIOSPERMS. 
547 
mature, the filaments appear as if they sprang from the inside of the perianth ; 
the earUest stages of development show, however, that the perianth-leaves and the 
stamens spring in succession and separately from the receptacle ; it is not till a later 
period that intercalary growth begins at the part of the receptacle from which both 
spring ; in this manner a lamella grows up which structurally forms the basal portion 
of the perianth-leaf, and which at the same time bears the stamen, so that the 
appearance is presented as if the stamen sprang from the centre of its inner surface. 
This is shown in Fig. 370, ^, where /> is a perianth-leaf and a an anther sessile upon 
it ; the two stand at first distinct on the young receptacle one over the other ; the 
portion of leaf lying beneath a and p is not formed till a much later period by 
intercalary growth, and pushes up at the same time the true perianth-leaf p, and 
the stamen a. This kind of adhesion is especially frequent in those flowers whose 
petals have also become coherent laterally into a tube, such as Compositse, Labiatae, 
Valerianaceae, &c. On the other hand, the stamen may also become adherent 
in various ways to the gynseceum. In Sterculia Balatighas (Fig. 371) this structure 
is only apparent, depending simply on the small stamens, which are placed close 
beneath the ovary, becoming raised up together with it by the elongation of a 
part of the receptacle ; from their small size they appear like a mere appendage of 
the large ovary ; the part which bears both the organs, the Gynophore^ is therefore 
in this case an internode of the floral axis. Much more complicated is the history 
of the formation of the true Gynostemium (column) which is formed above an 
inferior ovary, as in the Aristolochiaceae, and especially in the Orchideae, where 
these adhesions and displacements of the parts of the flower are also combined with 
abortion of certain members. Since these relationships will be explained in the 
sequel, the examination of Fig. 372 will suffice for the present, where the flower of 
Cypripediuni is represented from the side (^), from behind (^)j and from front (C), 
after removal of the perianth (/>/>). /* is the inferior ovary, ^j- the gynostemium, 
resulting from the adhesion of three stamens — two of which {a a) are fertile, while the 
third (s) forms a sterile staminode — with the carpel, the anterior part of which bears 
the stigma (;/). In this case the gynostemium consists entirely of coherent foliar 
structures, or of the basal portions of the staminal and carpellary leaves, both of 
Fig. 370,— Flower oi M^tii,i^iesta ,s'^abratci ; A before open- 
ing- ; B open ; C the gyuoeceum, the gyiiophore ; D hori- 
zontal section of the ovary ; E fruit ripening on its pedicel. 
Fig. 371. — Flower o{ Sterciclia Balaitshas ; 
A, the gynophore, f ovary, 71 stigma ; B hori- 
zontal section of the ovary. 
N n 2 
