88 
ALNUS 
This is the common form of hilly and northern localities, though it also occurs to some extent in southern 
England, at least as far south as Somerset and Suffolk; West Riding of Yorkshire, northwards at least to 
Caithness-shire. 
Sweden, Denmark, Germany, France, Austria-Hungary, and doubtless elsewhere. 
Alnus glutinosa occurs throughout the British Isles, northwards to Zetland ; in wet places, by 
stream-sides, in alluvial meadows, and in fens ; not growing well unless its roots are supplied with 
water which is well aerated, rare in places where the water is stagnant, and not thriving where the 
water is markedly acidic ; ascending to about 330 m. (doubtless as var. microcarpa ) in Perthshire. 
Often planted. 
Europe (northwards to 63° 47' N. in Norway); Caucasus to Japan; northern Africa (as var. 
vulgaris) ; North America (not indigenous). 
Order 5. URTICALES 
Urticales Lindley [Nixus Plant. 16 (1833) pro minima parte] Nat. Syst. ed. 2, 172 (1836) partim ; Engler 
Syll. 95 (1892); in Pflanzenfam. Nachtr. 346 (1897); Urticaceae Bentham and Hooker Gen. Plant, iii, 341 (1880). 
The Urticales connect the Amentiflorae with the Centrospermae. 
For characters, see page 3. 
Families of Urticales 
Family 1. Ulmaceae (see below). Trees. Flowers monoclinous, in more or less abbreviated 
cymose clusters. Filaments erect. Fruit (in the only British genus) a winged achene. 
^Family 2. Cannabaceae (p. 97). Herbs. Flowers diclinous. Filaments not bent inwards 
in bud. Fruit an achene. 
Family 3. Urticaceae (p. 98). Herbs (in the British species) with no latex. Flowers di- 
clinous. Filaments bent inwards in bud, springing back violently when ripe. Fruit an achene (in 
the British species). 
Family 1. ULMACEAE 
Ulmaceae Mirbel Lldm. ii, 905 (1815); Lindley Nat. Syst. ed. 2, 178 (1836); Engler in Engler und 
Prantl Pfla 7 izenfam. iii, pt. i, 59 (1894). 
Trees, with no latex. Buds distichous. Leaves distichous, more or less unequal at the base, 
serrate. Stipules caducous. Flowers monoclinous, in abbreviated axillary cymose clusters. Perianth 
with 4 — 7, usually 4 — 5 segments. Stamens as many as the perianth-segments. Ovary of 2 carpels, 
usually unilocular, rarely bilocular and the second loculus aborting. Ovules 1 to each loculus, 
pendulous from the apex of the ovary, anatropous or amphitropous. Style very short. Stigmas 2, 
free. Fruit (in the only British genus) a winged achene. Endosperm absent. 
Only the subfamily Ulmoideae (Engler in Pflanzenfam. iii, pt. i, 61 (1894)) is represented in the British flora: it is 
distinguished by its clusters of flowers, its pedicels in axils of scale-bracts, its extrorse anthers, its winged achene, and its 
straight ovary. 
13 genera and about 130 species, tropical and temperate zones. Only British genus: — Ulmus. 
Genus 1. Ulmus. 
Ulmus [Tournefort Inst. 601, t. 372 (1719)] L. Sp. PI. 225 (1753) et Gen. PI. ed. 5, 106 (1754); Engler 
in Engler und Prantl Pflanzenfam. iii, pt. i, 62 (1894). 
Trees, usually with suckers. Laminae more or less asymmetrical at the base, the bigger side 
facing the axis (cf. Carpinus), serrate, acute to acuminate ; rough or smooth above ; of the suckers, 
coppiced shoots, and summer-leaves, always rough above ; hairy below at least in the axils of the 
chief veins. Flowers protandrous, borne in the axil of one or two caducous bracts, the lowest 
