Cross — Eupatorium ageratoides and coelestinum. 263 



(b) The Corolla in Eupatorium coelestinum (Fig. 2) is 

 smaller and less spreading ; the lobes are shorter, more 

 rounded and less reflexed than in E. ageratoides. On the 

 outside, and near the base of the lobes, are found rounded 

 sessile hairs (Fig. 2 //) which in dried specimens are filled 

 with reddish purple pigment. The inner surface of each 

 lobe bears papillae only around its margin, and not uni- 

 formly over its surface, as in E. ageratoides. The lower 

 part of the corolla in each species is composed of rather 

 long, straight, thin-walled cells, which extend upward as 

 far as the attachment of the filaments. Above this point 

 the cell walls become slightly waved toward the top of 



the corolla. 



(a) The Stamens of E. ageratoides are borne on the 

 corolla tube alternate with its lobes. Each filament in cell 

 structure consists of two parts, the lower being composed 

 of long, thin- walled cells extending through two-thirds of 

 its entire length (Fig. 4 a). The other part, next to the 

 anther (.Fig. 4 b) is composed of oval or quadrangular cells 

 bounded by a thickened, beaded, strengthening wall, the 

 same in structure as the wall of the anther. The anther 

 consists of two lobes united by a connective which extends 

 upward between the lobes as an irregular, four-sided struc- 

 ture, broad on its external, and narrow on its internal face. 

 Each connective is expanded above into a transparent 

 deltoid process (Fig. 4 c) which unites with its neighbors 

 to form a pyramidal roof over the apex of the style, thus 

 protecting the more irritable parts from external influences 

 and the nectar from rain. The anthers are united by their 

 contiguous margins, and dehisce by introrse longitudinal 



slits, (Fig. 5). 



(b) The Stamens of E. coelestinum (Fig. 5) differ from 

 E. ageratoides (Fig. 4) only in being shorter and less 

 firmly united. 



(a) The Pistil of E. ageratoides is deeply cleft at the top 

 into two long style arms which are covered from their tips 

 downward over two-thirds their length with multicellular 



