398 MORPHOLOGY OF THE ANGIOSPERMS 



(frontispiece and Fig. 142A), in striking contrast to those in the 

 majority of the angiosperms, where petaloid staminodes and the "petals" 

 — which are morphologically staminodes — stand below the stamens. The 

 staminodes are highly important in pollination, which, in this genus, is 

 by beetles only. Basal connation holds all the stamens and staminodes 

 together, and they are abscised as a ring of organs after pollination. 



The Carpels. The many carpels are arranged in a flat spiral in the hol- 

 low receptacle (Fig. 142D). Tightly packed, the flat-topped carpels 

 form a nearly flat, tessellated, gynoecial floor, enclosed by the staminodes 

 (Fig. 72A). The carpels are connate throughout their length, congeni- 

 tally in their basal halves, where no histological limitation is evident. 

 Epidermal layers persist in the distal parts. The individual, more or 

 less angular, carpels are prominently outlined on the "floor." Athough 

 appressed and coherent, the carpels are slightly open, and decurrent 

 stigmatic lines extend down along the margins, as far as the area of 

 complete connation. The stigmatic area of each carpel is a slight mound, 

 with projecting papillae and a slitlike opening. The numerous ovules 

 are borne near the margins, apparently much as are those of Degeneria. 

 The carpels are primitive in form, showing no external evidence of a 

 style; the locule is slightly narrowed distally, but ovules are borne close 

 to the top. The gynoecium resembles that of Zygogyninn in the Winter- 

 aceae in the congenital union of spirally arranged carpels, but the 

 receptacle is concave in Euponiatia and strongly convex in Zygogynum. 



Taxonomic treatments commonly describe the carpels as sunken in 

 the receptacle, as are those of Nelwnbo; they are closely connate, not 

 separated by tissues of the receptacle (Fig. 72A). 



Pollination. Pollination in Eupomatia is by beetles and, apparently, by 

 one species only. Other ranalian families — especially the Calycanthaceae, 

 Magnoliaceae, and Nymphaeaceae — are pollinated largely by beetles, 

 a method now shown by evidence from several fields to be primitive 

 for angiosperms. Probably the Eupomatiaceae show the most elaborate 

 adaptation to beetle pollination; no other family is visited by only one 

 species of beetle. The fleshy, brightly colored staminodes are the organs 

 chiefly connected with pollination. In E. laurina, the outer staminodes 

 are spreading and erect (Fig. 142A); the inner are shorter and inflexed, 

 tightly enclosing a gynoecial chamber (Fig. 142C), with clusters of 

 stigmatic papillae scattered over the floor. Beetles are attracted by a 

 strong odor and eat their way into the chamber through the bases of 

 the staminodes. Within the chamber, they feed on the papillose margins 

 of the staminodes and on padlike food bodies on the ventral surfaces 

 of the staminodal tips which "roof" the chamber (Fig. 69F). The beetles 

 eat these food bodies extensively and remain long within the chamber. 

 In E. bennettii, the staminodes do not enclose the gynoecium chamber 



