182 PITTONIA. 
find so easy, does not satisfy; and Asa Gray, to the last, 
held our plants to be distinct from Senecio, though he did not 
distinguish them from Cacalia; but of his Cacalia! the 
Mesadenia species form with him, as with De Candolle, a 
subgenus; though his statement of its characters is not as 
strong as the plants warrant. The fullest diagnosis of the 
genus is that given by Rafinesque; and the species may 
bear names as follows: 
1. M. AvRIPLICIFOLIA, Raf. New Flora, iv. 79 (1836). 
Cacalia atriplicifolia, Linn. Sp. ii. 835 (1753). Senecio 
atriplicifolius, Hook. FI. i. 332 (1833). To this old species 
an improbable geographic range is ascribed, as from Canada 
and New York to Minnesota, and southward to the Gulf 
States. No doubt several species are included in it, which 
more thorough research may enable one to segregate, and 
perhaps to refer to one or more of the species yet unrecog- 
nized whieh Rafinesque described. 
2. M. renrrormis, Raf. l.c. Cacalia reniformis, Muhl. in f 
Willd. Sp. iii. 1735 (1803). Synosma reniformis, Raf. in 
Loud. Gard. Mag. viii. 247 (1832). Senecio Muhlenberg, 
Sch. Bip. in Flora, xxvii. 499 (1845). To this, numerous 
flowers to the head were erroneously attributed in the orig- 
inal description, which circumstance may have led Rafin- 
esque to suppose that it belonged to his genus S$ynosma. 
Its range is less extended than that of the first species, it 
being only eastern and southern in its distribution. 
3. M. ovata, Raf. L e. Cacalia ovata, Walt. Carol. 196 
(1785); Ell. Sk. ii. 310 (1824). Senecio Walteri, Sch. Bip. 
lc. Species of damp woods in the Gulf States, extending 
northward to Carolina. 
4. M. pivERsIFOLIA. Cacalia diversifolia, Torr. & Gray, 
Fl. ii. 485 (1843). From South Carolina to Florida, 12 
swamps. 
a licen 
! Syn. Fl. 396. 
