80 



INFLORESCEN-CE. 



Fig. 96, 



Fig. 97. 



are on different trees ; and of the order Octandria, because its 

 barren flowers liave eiglit stamens. 



The Spadix is an assemblage of flowers growing upon a com 

 mon axis, and surrounded by a spatha or sheath. 



Fig. 96, A, a, represents the blossom of the wild tur- 

 nip {arum) ; a, the spatha, "whicli is erect, sheathing, ob- 

 long, convolute at the base, and compressed above and 

 below the middle, h ; c represents the spadix, which, 

 from its club-shaped appearance, is called clavi-form 

 (from clava, a club). c\ 



At B is the spadix divested of the spatha ; a is the 

 clavi-form summit ; b, a ring of filaments without an- 

 thers ; c, a ring of sessile anthers ; d, a dense ring of pis- 

 tillate flowers with sessile stigmas ; each ovary produces 

 a one-celled globular berry. This plant is of the class 

 Moncecia, because its staminate and pistillate flowers are separate, but yet grow on 

 the same plant ; it is in the order Polyandi-ia, because its stamens are numerous. 

 a. The floral axis sometimes assumes a leaf-like 

 or pltylloid appearance (from phyllon, a leaf, and 

 eidos, form), as in Xylophylla, Fig. 97, a, where 

 the clusters of flowers are developed in a centrif- 

 ugal or cymose manner ; sometimes a flattened 

 Seduncle composed of adhesions of several pe- 

 uncles, forms a crested summit covered with 

 pointed bracts, and supporting flowers as in the 

 cockscomb (Celosia, Fig. 97,6); in the Vallisneria, 

 spiralis (Fig. 9*7, c), the flowers standing on spiral 

 peduncles are by their uncoiling raised" to the 

 surface of tlie water previous to their becoming 

 fertilized. The different kinds of inflorescence 

 are chiefly determined by the elongation or short- 

 ening of the axis, and the presence or absence of 

 pedicels or stalks to the flowers. Thus, a spike is 

 a raceme in which the flowers are not stalked ; 

 the umbel is a raceme in which the primary axis is 

 shortened ; the head is a spike in which the same 

 shortening has taken place. The centrifugal and 

 centripetal modes of inflorescence are sometimes 

 combined in the same plant ; in some compound 



flowers the heads of flowers taken as a whole are developed centrifugally, the ter- 

 minal head fii'st ; while the florets, or small flowers on the receptacle, open cen- 

 tripclally, those of the circumference first. 



85. The KECEPTACLE is the termination of the floral axis, the 

 summit of the peduncle upon which the flowers exj^and ; it is 

 not in reality a proper organ, though from the importance of 

 this point of the stem it is spoken of as such. The summit of 

 the peduncle is usually somewhat enlarged, to allow the develo2> 

 ment of the envelopes. When it forms a fleshy; ring surround- 

 ing the base of the carpels, as in the orange, it is called a disJc. 

 The receptacle is also called the cUnantlie (from Mine., bed, and 

 antlws.) flower), and sometimes the torus (from the Latin, signify- 

 ing bed). In simple flowers, as the tulip, the receptacle is scarce- 



Spadix— Various ai)peajances of the floral axis —85. Wliat is the receptacle ?— Different names of 

 the receptacle. 



