6 MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA UNIVERSITY 
MORPHOLOGY. 
ORGANS OF VEGETATION. 
Most of the members of the tribe are perennial herbs. The perennial portion con- 
sists generally of a short ascending rootstock, densely covered with remains of basal 
leaves and their scarious stipules. ‘To this is sometimes added a deep woody tap root. 
In species growing in arid regions the rootstock is generally very thick and woody and 
often much branched. Arctic and alpine species are generally cespitose. A few species 
of Potentilla are annuals or biennials with a branching root. Among ours P. fruticosa 
L. is a shrub 1-4 feet high and P. tridentata Ait. is also somewhat shrubby. 
The flowering stem is so variable that very little may be said concerning it in this 
connection. In the alpine and arctic plants it is often subscapose. In Duchesnea and 
some species of Potentilla, the stem is prostrate and rooting. Fragaria, Argentina 
(Potentilla Anserina, Egedii and anserinoides) and sometimes Duchesnea produce true 
runners. 
The inflorescence is more or less distinctly eymose. Where the stem is very leafy 
and the upper leaves not much reduced, the flowers become apparently axillary (the 
supina and argentea) groups of Potentilla. In Duchesnea, Argentina and the Tormentilla 
groups of Potentilla, the flowers are borne on long axillary pedicels. 
All species, so far as I know, have stipules. Those of the basal leaves are, as a rule 
scarious and more or less brown; those of the stem leaves, foliaceous. In Tomocarpa, 
(Potentilla fruticosa and its relatives) they are all scarious and more or less sheathing. 
The leaves are usually described as compound. This is, however, more or less 
erroneous, as the so-called leaflets are very rarely articulated to the rachis; but, on the 
contrary, often decurrent. Only a few, as for instance Sibbaldiopsis (Potentilla tridentata), 
have truly compound leaves. In this species there is an evident joint and the leaflets 
are tardily deciduous. As there is no name that applies to the principal divisions of a 
leaf divided entirely to the midrib, [ am obliged to use in the descriptions the word 
leaflets for these divisions. For the secondary divisions, I shall use segments, lobes or 
teeth, according to the depth of the incisions. 
In Fragaria, Duchesnea, Sibbaldiopsis and Sibbaldia the leaves are ternate. In 
Chamaerhodos they are twice ternately divided. In Potentil/la' they are pinnate or digi- 
tate, with three or more leaflets. In Comarwm and Horkelia (including Ivesia), they are 
pinnate and in the sub-genus Ivesia (except H. Webberi, Baileyi and saxosa ) the leaflets 
are very numerous, small and more or less imbricated. 
1 Here as well as for the most part in the following discussion, understood in its usual extensive limitation, 
