DICOTYLEDONES : POLYPETAL^ : THALAMIFLORai. 591 



SUB-CLASS II. POLYPETAL^E. 



Flowers usually ambisporangiate : perianth, usually consisting 

 of calyx and corolla, the petals being free. 



SERIES I. THALAMIFLOR.E. 



Sepals usually free : petals often indefinite : stamens hypo- 

 gynous, often indefinite : gynaeceum apocarpous or syncarpous. 



Cohort I. RanaleS. Flowers generally acyclic or hemicyclic : 

 perianth consisting of calyx only, or of calyx and corolla : stamens 

 usually indefinite : gynaeceum apocarpous, sometimes reduced to a 

 single carpel ; very rarely syncarpous, with a multilocular ovary. 

 Seed with or without endosperm. 



Order 1. RANUNCULACE.E. Perianth either consisting of a petaloid 

 calyx, or of calyx and corolla, usually spiral : stamens numerous, 

 occupying several turns of the spiral, or arranged in several alter- 

 nating whorls; anthers usually with lateral dehiscence, sometimes 

 extrorse or introrse : carpels numerous, spirally arranged ; rarely 

 one only ; the ovules are disposed on the connate margins of 

 each carpel, that is, in two rows down the ventral suture ; in 

 several genera the number of the ovules in each ovary is reduced 

 to one, which then originates from either the upper or the lower end 

 of the cavity of the ovary : seed with endosperm. They are almost 

 all herbaceous plants, and are either annuals or they have perennial 

 rhizomes ; they have no stipules, but they have amplexicaul leaves. 



Tribe 1. Anemonea. Petals generally replaced by stamens : sepals frequently 

 petaloid : ovaries numerous, each containing a single suspended or ascending 

 anatropous ovule ; fruit consists of a number of achenes. 



The genus Clematis consists of shrubs which creep, or climb by their petioles, 

 and have opposite leaves, and a petaloid usually valvate calyx. Clematis 

 Vitalba, the Old Man's Beard, is common in hedges ; it has a greenish-white 

 calyx, and fruits with long feathery styles ; C, Viticella, patens, and others are 

 cultivated as decorative plants. Atragene alpina, occurring in the Alps and in 

 Siberia, has its external stamens converted into petaloid staminodes. 



Thalictrum ; the species of this genus, as T. ruajus, minus, flavum, and 

 alpinum, the Meadow-Rues, have stems well covered with leaves, and flowers 

 with an inconspicuous, fugacious, 4-5-leaved calyx, and a flat receptacle. 



Anemone haa an hemispherical receptacle (Fig. 397 A t), and a petaloid, 

 usually 5-6-leaved calyx. In most of the species the underground rhizome 

 elongates into an erect scape which bears a single whorl of three bracteoles form- 

 ing an epicalyx (p. 494), beneath the terminal flower. In A.nemorosa, ranun- 

 culoides, and others, these bracteoles resemble the foliage-leaves, and often bear 

 flowers in their axils ; but in A. Pulsatilla, and others, they differ from the foli- 



V. S. B. Q Q 



