1646 A TEXTBOOK OF THEORETICAL BOTANY 



or inferior. The ovules are axile or parietal and there may be one or many 

 in each loculus. The seeds may or may not have endosperm and the embryo 

 is usually minute. 



Many are trees or shrubs, a few are climbers, while at the same time 

 there are a large number of herbaceous forms. 



The Rosales as conceived by Engler was a very large and rather indefinite 

 order containing some twenty families, between many of which there are 

 few points of similarity. Hutchinson has attempted to circumscribe the 

 group by splitting up the old Englerian order into a number of distinct 

 orders, which has in some ways simplified matters. On the other hand his 

 treatment has necessitated the rearrangement of a number of genera into 

 new or different families. Thus, for example, he would remove some of the 

 genera of the Saxifragaceae, redistributing them among three families and 

 placing them in a new order along with certain other Englerian families 

 of the Rosales. The method of treatment adopted here is a combination of 

 Hutchinson's method with that of Engler's. 



Three orders are recognized. Firstly, the Rosales, which include the 

 Pittosporaceae, placed in the Pittosporales by Hutchinson; the Hamameli- 

 daceae and Platanaceae, grouped by Hutchinson in the Hamamelidales, and 

 the Rosaceae. Secondly the Saxifragales, which include the Crassulaceae, 

 Cephalotaceae, Saxifragaceae and Podostemaceae. Thirdly the Legu- 

 minosae which are separated into Mimosaceae, Caesalpiniaceae and Papi- 

 lionaceae. The diagnosis at the head of the section therefore applies to the 

 Rosales as here treated. We shall consider the Rosaceae in detail, but must 

 first refer briefly to the more outstanding features of other families belong- 

 ing to the order, which are given in the above list. 



The Pittosporaceae are mostly trees or shrubs, though many are 

 climbers. The leaves are simple, evergreen, alternate or whorled, and are 

 devoid of stipules. The flowers are pentamerous, the gynoecium consisting 

 of two carpels. The seeds are mostly immersed in a viscid pulp and 

 often remain sticky for a long time even when dry. The family is a small 

 one containing some nine genera and about 200 species which are, with 

 the exception of Pittosporum, confined to Australia. Pittosporum which 

 contains about seventy species is common in the tropics and sub-tropics 

 and several species are with some difficulty cultivated out of doors in 

 Britain. The bright evergreen foliage is much used in winter house decora- 

 tions. The timber is used for high-class furniture in Australia. Billardeira, 

 with nine Australian species, is sometimes cultivated in greenhouses. It 

 is an evergreen climber with coloured fruits. 



The Hamamelidaceae are trees or shrubs with alternate leaves 

 and paired stipules, which are normally persistent and sometimes large. 

 The floral parts are in fours and the calyx tube is adnate to the bicarpellary 

 ovary. It is quite a small family with only fifty species grouped in eighteen 

 genera, but a number of them are well known either on account of their 

 timber or because their flowers, which are produced early in the year 

 before the leaves, make them desirable shrubs for early spring decoration. 



