UMBELLIFERA E 
597 
P 4 — 8 and as many sta. with a i-loc. ovary. [See art. Chalazo- 
gamae.] The fruit is a samara, adapted to wind-dispersal. The elm 
supplies a very valuable timber. 
Umbellales (Benth.-Hooker). The 15th cohort of Polypetalae (p. 134). 
Umbelliferae. Dicotyledons (Archichl. Umbelliflorae). About 180 
gen. with 1400 sp., cosmop., but chiefly N. temp. Many in Brit. 
Most of the order can be recognized at first glance by their habit; 
they are herbs with stout stems whose internodes - are hollow, and alt. 
exstip. sheathing leaves with their blades much divided in a pinnate 
manner. A few, e.g. Hydrocotyle and Bupleurum, have entire 
leaves. The infl. is usually a compound umbel. At the top of the 
stalk, which bears each partial umbel, an involucre of bracts is often 
found (the bracts of the outer firs.), and a similar larger involucre 
often occurs at the top of the main stalk bearing the compound 
umbel; the latter is sometimes termed the involucre in contra- 
distinction to the involucels of the partial umbels. A terminal flr. 
often occurs, e.g. in Daucus. In a number of genera belonging to 
§ A (below) simple umbels occur (e.g. Astrantia, Hydrocotyle) ; these 
are cymose in type (as the non-centripetal order of opening of the 
firs, clearly shows) and are often arranged in cymose groupings, e.g. 
in Sanicula. Eryngium has a cymose head. Some sp. of Xanthosia 
and Azorella have such cymose infls. reduced to single firs. These 
cymose infls., like the racemose, have often involucres of bracts. 
Fir. usually $ and regular (see below), epigynous. K 5, usually 
very small, the odd sepal p^oterior; C 5 (rarely o), usually w T hite or 
yellow; A 5, with introrse anthers. On the top of the ovary is an 
epigynous disc prolonged upwards into the two short styles. G (2), 
antero-posterior, 2-loc.; in each loc. one pendulous ovule, anatropous, 
with ventral raphe. 
The massing of the firs, into dense infls. makes them very con- 
spicuous (cf. Compositae), and this is aided by the zygomorphism of 
the corolla so often seen; the outer petals of the outer firs, of the 
umbel are drawn out (cf. Cruciferae) so as to form a sort of ray to the 
umbel. Honey is secreted by the epigynous disc; it is therefore 
accessible to all kinds of insects, and the order must be placed in the 
floral class A (p. 89), the lowest of all. [See p. 72.] The chief 
visitors are flies ; bees form only a small proportion of the total. 
The firs, are extremely protandrous; in most sp. the male stage is 
over in all the firs, of an umbel before even the outer ones have 
begun the female stage. 
The ovary ripens into a very characteristic fruit, a dry schizocarp, 
which splits down the septum between the cpls. into 2 mericarps, 
each containing one seed. The two are generally held together at 
first by a thin stalk (carpophore) running up between them. The 
structure of the pericarp is of great importance in determining the 
genera. It is nearly always necessary to have ripe fruit in order to 
