11 
may not extend beyond its Summit in any form, in which case it is 
said to be obsolete^ or it may appear at the top of the ovary as five 
persistent teeth or lobes, minute or somewhat conspicuous. The 
presence or absence of these “calyx-teeth” furnishes a character 
used in generic descriptions. 
Petals. The deciduous petals are inserted at the edge of an 
epigynous disk, and are usually white or yellow, although in some 
species they are blue, or even pinkish to dark purple. Usually 
they are concave, with an inflexed tip or acumination; and some- 
times at the flexure the acumination becomes so impressed as to 
give an emarginate or 2-lobed appearance. Much use has been 
made of these characters in generic descriptions, but among our 
North American forms we have found such uniformity that char- 
acters drawn from the petals are of no value, with the single ex- 
ception of the genus Heracleum. 
Stamens. From the 5 alternate distinct introrse stamens no 
characters are to be drawn. In general, UmbellifertB seem to be , 
protandrous, though protgyny has been observed in a few genera, 
such as l^haspium.! Sanicula and Erigenia. 
Pistil. A description of the bicarpellary pistil, surmounted 
by the disk from which arise two distinct styles either directly or 
with an intervening stylofodhim., which is either depressed or more 
or less conical, is better included under the discussion of the very 
important fruit structures. 
Fruit. — In no family of plants does the fruit furnish more 
certain diagnostic characters than in the Umbelliferce. So definite 
are tbev that the fruit alone can be made to determine the genus, 
and in most cases the species, while in every case it is an essential 
part of the description. This indicates at once an unusual amount 
of differentiation in the fruit structures, and great diversity in their 
display. 
The two carpels face each other, and are in contact at first by 
their commissural or ventral faces, but eventually separate. The 
fruit is compressed laterally (at right angles to the plane of the 
commissural faces), or dorsally (parallel with the commissural 
plane), or not at all. As the two carpels are but repetitions of 
each other, a description of structure may be confined to a single 
one. The surface of the carpel is usually marked by five ribs or 
\ 
V 
