478 



DICOTYLEDONES. 



there is one large projecting placenta, or two plate-like placentae 

 (the bent back edges of the carpels) studded with ovules. Fruit 

 a capsule, with many extremely small seeds. Begonia. 



420 species ; almost all from the Tropics (Am., Asia). Many species, with 

 varieties and hybrids, are ornamental plants in houses and conservatories, 

 chiefly on account of the form, colour and markings of their leaves ; but also 

 for their very beautiful flowers. They reproduce easily by adventitious buds 

 from leaves and portions of leaves placed on damp soil ; some have bulbils. 

 Like the OxalideEe they contain an acid sap. 



Order 8. Cucurbitacese. The flower is epigynous, and, as a 

 rule, is also provided with a leaf-like, cup- or bell-shaped receptacle 

 above the ovary, to which the perianth and stamens are attached ; 

 the flowers are regular, unisexual, with rudiments of the other sex r 

 and 5-merous : sepals 5, narrow and pointed, with the median 

 sepal posterior (Fig. 517), petals 5, stamens 5, and carpels 3 

 (rarely 4-5) ; the corolla is gamopetalous in the majority, poly- 

 petalous in some ; generally plicate- valvate in the bud. The anthers 



Fio.517. Eclallium agreste. Diagram of a $- and a ? -flower. 



in the <$ -flowers are extrorse, and monoihecious. i.e. only one half of 

 each of the anthers of the 5 stamens is developed, the pollen-sac hav- 

 ing frequently a peculiar <^>-shaped curve (Fig. 518 A, B) ; the 

 stamens are either all united into a column (e.g. in Cucurbita), or 

 they are united in pairs, so that only one remains free (Figs. 517 A ; 

 518 A} ; in the latter case there appears to be one small stamen 

 with a cx^ -shaped, curved pollen-sac and two larger ones, each with 

 two curved pollen-sacs placed as in Fig. 517 A. The original form 

 appears to be Feuillea with free petals and 5 free stamens. Some- 

 times the rudiment of a gynceceum is present. The carpels are 

 united inco an ovary with 3 (4-5) placentae formed by their united 

 edges. These are thick, fleshy, and bifid, bearing a number of ovules 

 on each s ; (le (Figs. 517 B: 518 C, D) ; in general the placentae are 



