The section Tuberarium of the genus Solanum in Mexico and 
Central America 
P. A. RYDBERG 
This section belongs to the subgenus Pachystemon of Dunal, 
t. €., the anthers are short, thick, subcylindric or oblong, not 
attenuate at the apex. It isin general characterized by odd-pin- 
nately dissected leaves, by terminal and lateral corymbiform or 
racemiform cymes, a corollas, pedicels with an articulation, 
and,as the name indica PI y with tuber-bearing stolons. 
Some botanists may ie been inclined to separate it as a genus 
distinct from Solanum, and Carl Bérner* united the section with 
Lyco persicum into a new genus Solanopsis. None of the char- 
acters by which the section is separated from the rest of the genus 
holds, however. Solanum bulbocastanum Dun., S. muricatum 
Ait., S. apalophyllum Dunal, S. simplicifolium Bitter, and S. 
morelliforme Bitter, which evidently belong to this section, have 
simple leaves and several species in the sections MORELLA and 
DULCAMARA have pinnatifid leaves. The pedicels are usually 
articulate some distance above the base, but in some species the 
articulation is practically basal. In the rest of the genus it is 
basal but often obsolete. The shrubby species of TUBERARIUM 
bear, as far as known, no tubers and in several of the herbaceous 
ones no tubers have as yet been found. There are therefore no 
constant characters to separate the section generally from the 
rest of the sections included in the subgenus PACHYSTEMON. 
Bittert has shown that there exists still less reasons for uniting 
the section with Lycopersicum. 
Since Dunal’s monumental work on Solanum in De Candolle’s 
Prodromus,t very little systematic work on this group has been 
made until in the last decade. Dunal divided the section into 
two groups “ Potatoe,’’ with interruptedly pinnatifid leaves, and 
“Pterophyllum,” with regularly pinnatifid leaves. As the pre- 
sence or absence of smaller intermittent lobes vary in the same 
* Abh. Nat. Ver. Bremen 21: 282. I9g12. 
j Rerpert. 11: 255-260. 1912. 
¢D. C. Prod. 13": 27-43. 1852. 
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