516 



ORCHIDACEJS. 



next the hilum. Perennial herbs or shrubs, with fibrous or tubercular 

 roots (fig. 121), either no stem or a pseudo-bulb, entire parallel-veined 



Figs. 735-741. Flower of Spiranthes autumnalis, to illustrate the natural order Orchidaceas. 



Fig. 735. Flower after the ovary has twisted on itself seen laterally, o, Ovary with the 

 adherent perianth, c e, Outer divisions of the perianth, called by some calyx, and by Lindley 

 corolla, c i, Inner divisions of the perianth, called by some the corolla, and considered by 

 Lindley as petaloid stamens. /, The labellum or lip, being the lower of the three inner seg- 

 ments. 



Fig. 736. Diagram of the flower in the young state, before the twisting of the ovary has 

 taken place, a, The axis of the spike of flowers, pe, pe, pe, Outer perianth, pi, pi. Two divi- 

 sions of the inner perianth. I, Third division of the inner perianth, in this state placed next 

 the axis, e, Fertile anther. * s, Two abortive anthers or staminodia. o, Ovary. 



Fig. 737. --Summit of the flower cut vertically, o, Adherent ovary with parietal ovules, g. 

 i, Labellum or lip. s, Stigma, a, Anther. 



Fig. 738. Anther separated. Its inner surface shown with its two cells. 



Fig. 739. Granular pollen-masses taken from the anther. 



Fig. 740. Horizontal section of the ovary, with three parietal placentas bearing numerous 

 ovules. 



Fig. 741. A seed separated, with its externJ reticulated integument, t. 



Fig. 742 Embryo of Aceras anthropophora deprived of its integuments. 



Fig. 743. Pollen-masses (Pollinia) of Orchis maculata, with the grains united in little conical 

 masses, c, Caudicle terminated by the retinaculum and glands. 



Fig. 744. The conical masses which the pollen-grains form by their cohesion. 



