262 Cross — Eupatorium ageratoides and coelcstinnm. 



tected. There was no marked difference in the time of 

 maturing of the fruits, whether borne on the most vigorous 

 early plants, or on those selected at later periods, the same 

 number of days bringing about, as nearly as possible, the 

 same results in every instance. 



Inflorescence of Eupatorium ageratoides and Eupato- 

 rinm coelestinum : Each capitulum is surrounded, and, in 

 early stages of development, completely covered in by the 

 involucre. E. ageratoides produces rather open panicles 

 of capitula with 12 to 17, commonly 15 white florets of deli- 

 cate texture on a flat disk-like receptacle. E. coelestinum 

 bears compactly-clustered panicles, and for the massing of 

 a greater number of florets the receptacle is prolonged 

 upward into a sharp-pointed cone, each of which bears 

 from 46 to 60 florets of a bluish purple color. In both 

 species the pappose rudiment of the calyx (Fig. 8 m) con- 

 sists of a series of long multicellular hairs, the bases of 

 which are surrounded by a very delicate tissue (Fig. 8 n) 

 which adheres to the torus when the pappose hair is 

 removed from, the margin. The corolla in Eupatorium 

 ageratoides consists of a lower tubular portion, expanding 

 into an upper cup-like form and terminating in five 

 corolla lobes. These lobes bear on the outside, and near 

 their bases, multicellular hairs (Fig 1 h) longer than the 

 lobes themselves. These hairs occupy an upright position 

 until the corolla is expanded, when, by the recurving of the 

 petals, they are thrown back, become flaccid and wither 

 with the corolla. In structure the corolla exhibits not 

 only the long external hairs just referred to, but the inner — 

 or when expanded, the upper — surfaces of the petals are 

 covered with large, rounded, closely-set, tubular papillae, 

 (Fig. 1 p) which resemble the sweeping hairs on the 

 style, but differ from these in being shorter and in dimin- 

 ishing to slight swellings at the base of the corolla lobes, 

 where they finally disappear. These updirected outgrowths 

 may be of use to insects in affording them a firmer footing 

 when visiting the florets for pollen and nectar. 



