Ixxii INTRODUCTION. 



(Male flowers in globular heads in a terminal raceme. Females 

 axillary, joined two together in a large prickly burr, with 

 incurved points Xanthium (p. 235). 

 Flowers, male and female, distinct, or in heads, not prickly . 134 



■to a f Male perianth of 4 parts 135 



\Male perianth of 5 or 3 parts . . Chenopodiaceje (p. 370). 

 ( Leaves all radical, linear and fleshy, or transparent. Marsh 



135-j or water plants 136 



[ Stems leafy. Leaves flat . . . . Urticacb^j (p. 398). 



(Male flowers one or two on a stalk, with very long stamens. 

 Females sessile . . . . . Littorella (p. 367). 

 Male and female flowers minute, mixed together in a small 

 terminal head Eriocaulon (p. 476). 



. ^/Leaves opposite, simple .... Mercurialis (p. 395). 

 \ Leaves alternate, pinnate . . . . Poterium (p. 141). 



f Leaves alternate, with sheathing stipules. Stamens 6. Nut 



enclosed in the calyx Bumex (p. 379). 



Leaves small and fine, in tufts. Stamens 6. Fruit a berry 

 138 » Asparagus (p. 459). 



Leaves small and heath-like. Stamens 3. Fruit a berry 



Empetrum (p. 396). 

 Leaves radical, long, arrow-shaped. Stamens and carpels 

 numerous. Aquatic plant . . . Sagittaria (p. 431). 



-oq /Flowers all male (a male specimen) 131 



\ Flowers all female (a female specimen) 140 



r Perianth 6 -cleft, the 3 inner segments larger. Styles 3, with 

 short fringed stigmas. Leaves alternate or radical. 



Bumex (p. 379). 

 140^1 Perianth 2- or 4-cleft. Stigma single, sessile, tufted. Leaves 



opposite, stinging ...... Urtica (p. 399). 



Perianth 3-cleft. Styles 2, simple. Leaves opposite, not sting- 

 ing Mercurialis (p. 395). 



3. Trees or Shrubs, 



-.- /Leaves opposite 142 



\ Leaves alternate or in tufts 145 



- ._/ Leaves divided, lobed or angular, deciduous .... 143 

 \ Leaves entire, evergreen . . . . . . . . 144 



{Leaves lobed or angular. Stamens about 8. Fruit with two 

 diverging wings Acer (p. 96). 

 Leaves pinnate. Stamens in pairs, collected in clusters. Fruit 

 with one erect wing .... Fraxinus (p. 297). 



(Parasitical shrub with green dichotomous stems. Fruit a berry 

 Viscum (p. 204). 

 Erect branching shrub with shining leaves. Fruit a few- 

 seeded capsule . . ... . . Buxus (p. 396). 



'Male flowers in catkins, separated by scales only. Females 

 solitary or in clusters, or in catkins, usually different from 



145-[ the males 146 



Flowers hermaphrodite or diclinous, each with a distinct 

 perianth 147 



