=A.= ULMEÆ. The fruit is a _winged nut_ (Fig. 339), the embryo straight, without endosperm. Anthers extrorse.--_Ulmus_ (Elm). The flowers are situated in inflorescences which develop from the lower buds of the shoot of the preceding year. ~The lowermost bud-scales are empty, the uppermost support either solitary flowers, or small, dichasial or unipared scorpioid inflorescences. The terminal bud on the vegetative shoot quickly falls off, and the upper lateral bud continues the growth sympodially. Flowering takes place before the leaf-buds open. The flowers are wind-pollinated and have no honey. Fossil species have been found in the Oligocene.~ 20 species; North Temp. (2 species in this country). Important as timber. The Cork-elm (_U. suberosa_) has a rather thick cork, which, however, is of no technical use. The bast is used as Lime-bast. =B.= CELTIDEÆ. The fruit is a drupe, the embryo curved, with folded or rolled up cotyledons, with or without endosperm. The anthers are introrse. The flowers are borne on a shoot of the same year. _Planera_ (N. America); _Zelkova_.--About 114 species; especially N. Temp., Trop. [Illustration: FIG. 339.--_A Ulmus campestris_, flower with exceptionally aborted gynœceum; _B_, _U. effusa_, flower with 8 stamens; _C_, _U. campestris_, fruit opened in front to show the seed pendulous from the apex of the loculus; one loculus is aborted.] Order 2. =Urticaceæ= (=Nettles=).--The majority of species are herbs with simple, stipulate leaves; they have _no latex_; _stinging hairs_ abundant. The flowers (Fig. 340) are _unisexual_, generally 2-merous and arranged _in clusters_, which are united into catkin-like inflorescences. The perianth is composed very often of 4 (2 + 2) free, or in the ♀-flowers generally united, green leaves; the 4 (2 + 2) stamens are opposite the perianth-leaves, the filaments are _bent inwards_ in the bud and throw themselves elastically towards the outside. The gynœceum has _one style_ and _one stigma_ (capitate or brush-like, Fig. 341); the ovary is unilocular, with _one orthotropous_, _erect_ ovule (all other orders of this family have inverted or curved ovules). Fruit, a nut or drupe. _Endosperm present_ (in _Urtica_ very little), oily. Embryo straight. ~The STINGING HAIRS are club-shaped, very turgid, and provided with a siliceous, brittle apex, which breaks off in an oblique direction and allows the poisonous cell-sap to be forced out. In many tropical Nettles this is so strong that it may produce partial paralysis. There is no rudiment of an ovary in the ♂-flowers (Fig. 340 A). The PERIANTH in the ♀-flower differs from that of the ♂ in having the two internal leaves generally much larger and enveloping the fruit (Fig. 340 _B_); it often happens that all the perianth-leaves are united to form a gamophyllous envelope. ☿-flowers may occur among the others.--THE INFLORESCENCES among our native species are dichasia, which become transformed into unilateral