400 THE NETTLE FAMILY. [Parietaria. 



II. PARIETARIA. PELLITORY, 



Herbs, with alternate, often entire leaves, and not stinging. Flowers 

 in small axillary clusters, surrounded by a few bracts, often united into 

 a small involucre. Male flowers like those of Urtica, but usually very 

 few. Females with a tubular or campanulate, 4-lobed perianth, enclos- 

 ing the ovary and adhering to the seed-like fruit. Stigma single, tufted, 

 sessile or with a distinct style. Besides these there are a few herma- 

 phrodite flowers, which become enlarged after flowering, but seldom 

 ripen their seed. 



A genus of several species, chiefly from the Mediterranean region and 

 central Asia, with one American one, widely spread over a great part of 

 the world. 



1. P. officinalis, Linn. (fig. 906). Wall P. A small, branching per- 

 ennial, erect the first year, afterwards usually diffuse or procumbent, 6 

 inches or rarely a foot long, more or less downy with short soft hairs. 

 Leaves stalked, varying from ovate to oblong, quite entire. Flowers in 

 sessile clusters, the involucre very small, consisting of 2 or 3 divided 

 bracts. P. diffusa, Koch. 



On old walls, and in waste, stony places, throughout Europe and 

 Russian Asia, except the extreme north. Common in Britain, but rare 

 in the north. Fl. the whole summer. 



III. HUMULUS. HOP. 



A single species, differing from all other Urticaceas by its twining 

 habit, by the inflorescence, and by the seed, which contains a flat, 

 spirally coiled embryo, without albumen. 



1. H. Lupulus, Linn. (fig. 907). Hop. Rootstock perennial, the 

 stems annual, but twining to a considerable height over bushes and 

 small trees. Leaves opposite, stalked, broadly heart-shaped, deeply 3- 

 or 5-lobed, and sharply toothed, very rough but not stinging. Flowers 

 dioecious, the males in loose panicles in the upper axils, small, and of a 

 yellowish green. Perianth of 5 segments. Stamens 5. Female flowers 

 in shortly stalked, axillary, ovoid or globular spikes or heads, con- 

 spicuous for their broad, closely-packed bracts, each with 2 sessile 

 flowers in its axil. Perianth a concave scale enclosing the ovary. 

 Stigmas 2, long and linear. After flowering, the scales of the spike 

 (often called a cone) become much enlarged, quite concealing the seed- 

 like fruits. 



In hedges, thickets, and open woods, all over Europe and central and 

 Russian Asia, except the extreme north. Extends over most of England, 

 and is naturalised in Ireland and Scotland, having long been in general 

 cultivation. Fl. summer. 



LXX1I. ULMAOE5!. THE ELM FAMILY. 

 Trees or shrubs, differing from Urticacece in their flowers 

 mostly hermaphrodite, and the ovary generally 2-celled, although 

 the fruit has but 1 seed 



