Flower-clusters with an involucre and usually surrounded by woolly hairs. Female flowers without a perianth. 3 3. Involucral bracts free or united at the base only. Stem rough. Herbs undershrubs or shrubs.--Species 5. =Forskohlea= L. Involucral bracts united high up. Stem smooth. Herbs or undershrubs.--Species 5. Tropical and South Africa. =Droguetia= Gaudich. 4. Stipules absent. Leaves alternate, entire. Plants without stinging hairs. Female flowers in glomerules surrounded by an involucre; perianth 4-cleft. [Tribe PARIETARIEAE.] 5 Stipules present, very rarely rudimentary, but then leaves toothed. 6 5. Stem herbaceous. Flowers polygamous. Stigma spatulate and recurved.--Species 8. Some are used in medicine. “Pellitory.” =Parietaria= Tourn. Stem woody. Flowers unisexual. Stigma linear.--Species 1. Canary Islands. =Gesnouinia= Gaudich. 6. Plants with stinging hairs, very rarely (_Fleurya)_ almost glabrous, and then stigma linear-oblong and shortly papillose and perianth of the female flowers 3-4-partite. Perianth-segments of the female flowers 4, rarely 1-3. Embryo with orbicular cotyledons. [Tribe UREREAE.] 7 Plants without stinging hairs. 12 7. Fruit straight. Stigma penicillate. Leaves opposite. Herbs.--Species 10. They yield material for spinning and paper-making and are used as pot-herbs and in medicine. “Nettle.” =Urtica= Gaudich. Fruit oblique. Leaves alternate. 8 8. Stigma more or less capitate. Perianth surrounding the fruit fleshy. Shrubs or trees, rarely undershrubs.--Species 20. Tropical and South-East Africa. =Urera= Gaudich. Stigma linear or oblong. 9 9. Perianth of the female flowers reduced to a single, sometimes 2-parted, large segment, more rarely consisting of 2 unequal segments. Herbs with punctiform cystoliths.--Species 3. Tropics. =Girardinia= Gaudich. Perianth of the female flowers with 4 segments, of which 1-2 are sometimes rudimentary. 10 10. Cystoliths linear. Annual herbs. Fruit gibbous, as long as or longer than the perianth.--Species 7. South and Central Africa. They yield fibre and fish-poison. (Plate 32.) =Fleurya= Gaudich. Cystoliths punctiform. Perennial herbs or woody plants. 11 11. Fruit as long as or longer than the perianth, smooth.--Species 3. Central Africa. (_Urticastrum_ Heist.) =Laportea= Gaudich. Fruit much shorter than the membranous perianth. Shrubs.--Species 6. Madagascar, Mascarenes, East Africa. =Obetia= Gaudich. 12. (6.) Stigma penicillate. Perianth of the female flowers 3-partite, rarely 4-5-partite or rudimentary, free from the ovary. Embryo with orbicular or ovate cotyledons. Cystoliths linear. Herbs or undershrubs, rarely shrubs; in this case leaves penninerved. Stipules connate. [Tribe PROCRIDEAE.] 13