120 THE FLORA OF THE ALPS 
vessel an indehiscent nut. A very large order of herbs, 
shrubs, and trees, belonging chiefly to Tropical and Sub- 
Tropical countries, with very few European representa- 
tives ; not alpine. 
t, URTICA, Lourn. 
Flowers unisexual ; calyx 4-cleft; stamens 4; leaves 
opposite, stipulate, furnished with stinging glands. 
Our two English species of Stinging Nettle, U. dzozca, 
L., with dicecious ; and wrens, L., with moncecious flowers, 
are equally common in Switzerland. 
2. PARIETARIA, Tourn. 
Flowers in dense clusters, mostly unisexual; calyx 4- 
cleft; stamens 4; leaves entire, without stipules; pollen 
expelled in puffs by the bursting of the anther. 
P. officinalis, L., Wall-Pellitory, with its sub-species 
erecta and atffusa (ramifiora, Monch.); common on walls 
and rocks. 
3. HUMULUS,L- 
Flowers small, dicecious ; sepals 5 ; stamens 5; female 
flowers ‘in the axils of large membranous bracts, which 
form a dense catkin-like spike; ovary 1-celled; stem 
twining. 
H. Lupulus, L., Hop.; hedges, common. 
A. AIEMUS, Le: 
Flowers bisexual, in clusters; leaves with deciduous 
stipules ; fruit a 1-seeded samara. Trees with deciduous 
leaves. 
