52 ARKIV FOR BOTANIK. BAND 13. NIO 15. 



forms of the species do not live anywhere within its range. 

 In the northern part of it round-leaved forms with tawny 

 pappus dominate, towards the South narrow-leaved ones 

 with white pappus become numerous. It is a remarkable 

 fact that V. albicaulis thus on the confines of the range of V. 

 arborescens (L. ) Sw. becomes like that species, though al- 

 ways recognizable by the characters of the involucres and 

 by the acute basal lobes of the anthers. If this is due to 

 some ancient hybridization, or if V. albicaulis and V. arbo- 

 rescens are to be looked upon as rather recent offshoots .of 

 one species, the southern forms being almost unaltered descend- 

 ants of the common type, or if the fact of matter is, that either 

 of the species (most probably V. arborescens) on its migra- 

 tion has been altered by the force of climate into the 

 other, the forms in question owing their existence to a 

 particular intermediate climate, of course cannot be discussed 

 here. 



It may, perhaps, be of some use to characterize the most 

 prominent forms of the species and to give their distribution. 



1. The type of V. Sintenisii (Urb.) Gleason: Leaves 

 small, oblong (dimensions: 3X1,2 cm), obtuse or even emar- 

 ginated, thinly pubescent with appressed hairs, somewhat seri- 

 ceous-shining. Heads relatively small, about 8 mm long. 

 Pappus pale straw-coloured. This is the form of Porto Rico. 

 However, not all specimens from this island are true V. 

 Sintenisii Gleason. Some of them agree almost exactly with 

 the type of V. albicaulis Pers., for instance, Sintenis n. 

 470, others cannot be distinguished from V. emarginata 

 Wikstr., so Stahl n. 730. 



2. The type of V. albicaulis Pers. Leaves oval (dim. 

 5X3 cm), obtuse at the apex and shortly attenuate at base, 

 very thinly pubescent, not shining, grayish-green or grayish- 

 -olivaceous. Heads small, 6 7 mm long, in number 4 5 on 

 slightly recurved cymes, somewhat apart. Pappus very pale 

 straw-coloured. This form occurs in its most typical shape in 

 St. Croix, where it was collected by the ancient Danish bot- 

 anists. The original specimen at Paris came from Vahl, 

 as did the types of Eupatorium obtusifolium Willd. and Ver- 

 nonia Vahliana Less. 



To this approximate two forms, one having very large, acute 

 leaves (dim. 13 X 6,5 cm) and larger heads (9 10 mm long). 



