614 
ULMUS 
P 4 — 8 and as many sta. with a i-loc. ovary. [See Chalazogamae.] 
Fruit a samara. The elm supplies a valuable timber. [See Lubbock 
in Linn. Soc. Journ. 33, p. 236.] 
Umbellales (Benth. -Hooker). The 15th cohort of Polypetalae (p. 135). 
Umbelliferae. Dicotyledons (Archichl. Umbelliflorae). About t8o 
gen. with 1400 sp., cosmop., but chiefly N. temp. Many in Brit. 
Most can be recognized 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. Infl. usually 
a compound umbel. At the top of the stalk of 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 contradistinction to the involucels of the partial umbels. 
A terminal flr. often occurs, e.g. in Daucus. In a number of genera 
belonging to § A simple umbels occur {e.g. Astrantia, Hydrocotyle), 
cymose in type (as the non-centripetal order of opening of the firs, 
clearly shows) and 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., and 
these infls. have commonly involucres of bracts. 
Fir. usually £ and regular (see below), epigynous. K 5, usually 
very small, the odd sepal posterior ; C 5 (rarely o), usually white or 
yellow; A 5, introrse. On top of the ovary is an epigynous disc 
prolonged upwards into 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 conspicuous 
(cf. Compositae), and this is aided by the zygo- 
morphism of the corolla often seen; the outer 
petals of the outer firs, are drawn out (cf. Cru- 
ciferae) so as to form a sort of ray. Honey is 
secreted by the disc ; it is accessible to all insects, 
and the order must be placed in class A (p. 89). 
The chief visitors are flies ; firs, very protandrous, 
the male stage being most commonly over before 
the female begins. 
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 gener- 
ally 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 identify one of the U. The shape is often important; 
Floral diagram. 
