CLASSIFICATION OF DICOTYLEDONS. 223 



five of which have common representatives, but the last family 

 (Calycerece) has no members within our limits. 



The lower members of the order, e.g. various Rubiacece (Fig. 

 124, A, -ET), have the flowers in loose inflorescences, but as we 

 examine the higher families, the tendency for the flowers to 

 become crowded becomes more and more evident, and in the 

 highest of our native forms Dipsacece (Fig. 124, P) and Com- 

 positce (Fig. 125) this is very marked indeed. In the latter 

 family, which is by far the largest of all the angiosperms, 

 including about ten thousand species, the differentiation is 

 carried still further. Among our native Compositor there are 

 three well-marked types. The first of these may be repre- 

 sented by the thistles (Fig. 125, A). The so-called flower of 

 the thistle is in reality a close head of small, tubular flowers 

 (Fig. 125, (7), each perfect in all respects, having an inferior 

 one-celled ovary, five stamens with the anthers united, and a 

 five-parted corolla. The sepals (here called the "pappus ") (p) 

 have the form of fine hairs. These little flowers are attached 

 to the enlarged upper end of the flower stalk (receptacle, r), 

 and are surrounded by closely overlapping bracts or scale 

 leaves which look like a calyx; the flowers, on superficial 

 examination, appear as single petals. In other forms like 

 the daisy and may-weed (Fig. 125, F), only the central flowers 

 are perfect, and the edge of the inflorescence is composed of 

 flowers whose corollas are split and flattened out, but the 

 stamens and sometimes the pistils are wanting in these so- 

 called "ray-flowers." In the third group, of which the dande- 

 lion (Fig. 125, H), chicory, lettuce, etc., are examples, all of 

 the flowers have strap-shaped, split corollas, and contain both 

 stamens and pistils. 



The families of the Aggregates are the following : I. Rubiacece 

 of which Houstonla (Fig. 124, A), Galium (E), Cephalantlius 

 (button-bush), and Mitcliella, (partridge-berry) are examples; 

 II. Caprifoliacece, containing the honeysuckles (Lonicera) 

 (Fig. 124, /), Viburnum (6?), snowberry (Symphoricarpus), 



