552 



DICOTYLEDONES. 



equal value. If there are, for instance, 4 members in two succes>ive whorls, 

 they stand right above one another, and do not alternate. The development 

 and anatomical relations (the branching of the vascular bundles) also point to 

 the same conclusion. All the other groups of the order have only 

 2 small scale-like interpetiolar stipules, or they form, at the base of 

 the leaf-stalks an interpetiolar sheath, having often a toothed edge 

 (Fig. 586). Another characteristic feature in this group is that 

 the calyx is rudimentary, the corolla valvate (Fig. 588), and that 

 each of the two loculi of the ovary has only 1 ovule. The fruit is a 

 schizocarp dividing into 2 fruitlets (Fig. 590). The forms of the fruit, 

 as well as many other characters, as, for example, the epigynous flower, the 

 rudimentary calyx, the two free or almost free styles, present interesting 

 analogous resemblances to the polypetalous order of the Umbelliferffl. This 

 group has its home chiefly in the temperate regions of the northern 

 hemisphere, especially about the Mediterranean ; it is the only 

 group which occurs in this country, represented by 4 genera. 



658. 



5:0. 



589. 



FIGS. 558-590. Rubia tinctorum. 



FIG. 588. Diagram. FIG. 589. Longitudinal section of flower. 



FIG. 590. Longitudinal section of fruit (|). 



Galium (Cleavers) is almost destitute of a calyx ; it has a small 

 ^-partite, rotate corolla, 4 stamens, and 2 free styles. The fruitlets 

 are nut-like. The inflorescence is a paniculate dichasium passing 

 into helicoid cymes. Asperula (Woodruff) is distinguished from 

 the above by its salver- or funnel-shaped corolla. 1 style. Rubia 

 (Madder, Figs. 587-590) has almost the same form of corolla as 

 Galium, bub (most frequently) a b-merous flower, and the fruitlets 

 are "drupes." Sherardia (Field Madder) ; the flowers are clustered in closely 

 arranged cymes surrounded by an involucre ; the calyx has 6 distinct teeth, 

 while the number of petals and stamens is 4. The corolla is funnel-shaped. 

 Vaillantia. Crucianella. 



The DISTBIBUTION OF SEEDS, in some instances, is promoted by hooked append- 

 ages on the fruitlets (e.g. Galium aparinc). 



The small flowers of the Stellatse are frequently collected in compact inflor- 

 escences, and are therefore rendered more conspicuous; slight protandry is 



