DICOTYLEDONS : ARCHICHLAMYDEAE 237 



and many occur in Britain, where they are often cultivated 

 for their showy flowers. There is great diversity in the 

 flowers ; the perianth is often petaloid without differentia- 

 tion into calyx and corolla. The following should be 

 examined and their peculiarities noted : Meadow Rue 

 {Thalidrum), with small flowers and inconspicuous perianth, 

 Clematis (Fig. 109, p. 164), Anemone (Fig. no, p. 164), Marsh 

 Marigold (Fig. in, p. 164), and Christmas Rose (Helleborus), 



Fig. 164. Floral Diagram of Buttercup. 

 a, stamens ; br, bract ; c, carpels ; ca, sepals ; p, petals. 



with a petaloid calyx and no corolla, except in the latter. 

 In Caltha, honey is secreted by the carpels, and in the 

 Christmas Rose by small, tubular ' petals '. In the Butter- 

 .cups (Fig. 112, p. 166) {Ranunculus spp.) there is a calyx 

 and a conspicuous corolla, and the nectary is at the base 

 of the petals. In the Columbine (Fig. 130, 1, p. 186) 

 (Aquilegia vulgaris) the five petals form long, honey-secreting 

 spurs. In the Larkspur (Fig. 130, 3-5, p. 188) {Delphinium), 

 the spurred posterior sepal contains the two posterior honey- 

 secreting petals. In the Monkshood (Fig. 130, 2, p. 187) 

 [Aconitum Napellus) the posterior sepals form a large, blue 



