252 FAMILIES OF FLOWERING PLANTS. 
aceae: that is, the flowers are aggregated in an involucrate head; but 
there is this difference, that in the 
Compositae proper only part of 
the flowers have strap-shaped 
corollas, the others being tubular 
and inconspicuous, like those in 
the “center” of a so-called daisy 
flower. In some tribes, indeed, 
the flowers are alltubular. Onan 
examination of any Composite we 
can readily understand why this 
family illustrates the highest de- 
velopment among flowering plants, 
on the theory that separation of 
parts is an indication of primitive 
structure. For here the anthers 
and filaments are united into a col- 
umn; the corolla forms a tube; the @ 
calyx is in such intimate adher- 
ence to the ovary that it may be 
said to have disappeared; the 
ovary is one-seeded: the flowers 
are aggregated in a close head ; 
and the floral bracts are crowded 
into a calyx-like involucre. 
FIG. 223. A native species of golden-rod (Solidago 
juncea). After Britton and Brown, Ill. Fl. Northeast. 
Fic. 224. A western composite allied to the ‘‘ black-eyed Susan ”* (Ratibida 
columnaris). After Britton and Brown, Ill. Fl. Northeast. 
U.S. 
And thus, having found our way through the maze of plant fami- 
