EOSIFLORJ;. 



457 



The Rosifloras are on one side closely related to the Saxifragaceae (especially 

 through Spiraea) from which it is difficult to separate them, and to the Myrti- 

 florae ; on the other side they are allied, through the Mimosacae with the large 

 number of stamens, and through the Amygdalacese with its single carpel, to the 

 Leguminosas. The family begins with forms which have many-seeded 

 follicles, and passes on the one side to forms with nuts and drupes in perigynous 

 flowers, and on the other side to the Pomaceae. 



Order 1. Rosaceae. Herbs or shrubs, generally with com- 

 pound leaves and persistent (adnate) stipules, flower perigynous, 

 gynceceum formed of many free (therefore oblique) carpels, syncarps 

 with fruitlets of various kinds. The exceptions are noted under 

 the genera. 



I. SPIEJIE^: (Fig. 495) has 2-many ovules in each ovary, while 

 in the other groups there is generally only 1, and never more than 

 2 ovules in each loculus. There are generally 5 cyclic carpels and 

 the fruit is 5 follicles, which are not enclosed by the receptacle. 



FIG. 494. Diagram of Comarum FIG. 49f. Flower of Spiraea lanceolata. 



palustre. 



The majority are shrubs. Stipules are often wanting. Spiraea 

 (Meadow- Sweet). The flowers are generally borne in richly 

 flowered inflorescences of various forms. The carpels, in some 

 species, unite together and form a simple gynceceum with free 

 styles (an approach to the Pomacese). Closely allied to Spiraea are the 

 East Asiatic shrubs : Kerria japonica, which has solitary flowers, in this country 

 nearly always double (the fruit a nut), and Rhodotypus kerrioides which has 

 Opposite leaves, a remarkable feature among the Rosifloras ; it has a 4-merous 

 flower, a well developed disc inside the andrcecium, and a drupe. Closely 

 allied also is Gillenia (N. Am.) differing chiefly in the ascending ovules, Spiraea 

 having pendulous ovules, and a more tubular receptacle. 



The groups Quillajece and Neuradece form a transition from Spiraea to 

 Pomaceos, In the first group, which contains only trees or shrubs with generally 

 simple leaves, the carpels are either free or united (into a capsule) ; in the 

 second the receptacle unites with the carpels, which are themselves often united 

 together ; in this case, too, the fruit is a capsule. QuilJaja (S. Am.) ; Exochorda 

 (China). 



