MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA UNIVERSITY ) 
somewhat the same way from the lateral portion of the axis as the integuments of the 
seed do from the funiculus. It begins as an annular thickening some distance below the 
apex of the axis; this thickening enlarges in Fragaria, Comarum, Argentina, Sibbaldia 
and several Potentillac and Ivesiae to a nearly flat disk, bearing the bractlets, sepals, 
petals and stamens on its margin. More commonly, however, the margin curves up- 
ward and the disk becomes cup-shaped, campanulate or turbinate (in other tribes even 
tubular), enclosing the receptacle with its pistils and often exceeding it in height. 
As the epidermal tissue of the outer or lower surface of this cup is nearly the same in 
structure as that of the bractlets and sepals, it has usually been regarded as a part of the 
calyx. This view, although erroneous, is still adhered to in all our American works on 
descriptive botany. There is no need, however, of perpetuating a faulty application of 
the term calyx and I shall not use it in the sense given. As the term receptacular cup (or 
if elongated, receptacular tube), which expresses the correct idea, is very inconyenient in 
descriptions and almost wholly unknown to American botany,’ I shall adopt, in my 
descriptions, for convenience, the shorter term hypanthiwm for the cuplike expansion of 
the flower-axis and designate the free leaves of the outer set of floral envelopes by the 
word sepals. 
The inner surface of the hypanthium is covered with a more or less glandular 
tissue, which is generally thickened where the stamens are inserted. In Fragaria, 
Potentilla, ete., the distance between the base of the receptacle and the stamens is very 
small, while in Horkelia (including Ivesia ) these are quite removed from each other. 
FLORAL ENVELOPES. 
The sepals are in most species normally five in number, but in a few only four; they 
are inserted on the outer margin of the cup, as stated above, and more or less imbri- 
cated in the bud. Outside of the sepals and alternate with them, in all genera of the 
tribe, except Chamaerhodos, there is a set of similar often smaller organs, usually called 
bractlets. They have been regarded as representing a set of bracts, also united with the 
sepals or else a set of outer floral envelopes, an outer calyx. The view now most com- 
monly held is that each represents two united stipules as often found in opposite or 
whorled leaves. 
The petals are of the same number as the sepals and alternate with them. ‘They 
are inserted in the angle between the sepals and slightly inside the same. If the stami- 
niferous disk is thickened their insertion is just under its margin. 
The form of the petals is variable. In Potentilla proper they are most commonly 
1 So far as I know, no one in America has used the term, except myself in the Flora of Nebraska, part 21. 
