600 PART III. THE CLASSIFICATION OF PLANTS. 



Tribe 3. Polycarpece. Leaves with scarious stipules : calyx eleutherosepalous ; 

 the corolla is present, but the inner whorl of stamens is wanting: style 3-fid. 

 This group includes the British genus Polycarpon (Allseed) and others. 



Tribe 4. Paronychiece. Sepals distinct or coherent : the corolla and the inner 

 whorl of stamens are usually wanting : style usually bifid : ovary unilocular, 

 with 1-4 ovules : fruit generally indehiscent. 



The British genera are Scleranthus (Knawel), Herniaria, Corrigiola (Strap- 

 wort), and Illecebrum: they are small inconspicuous herbs, with scarious 

 stipules (except Scleranthus). 



The Paronychieae have also been placed, as a distinct natural order ILLECE- 

 BRACEvE, among the Monochlamydeaa. There is no doubt that they have 

 affinities with the Chenopodiales, and that they thus connect that cohort with 

 tLe Caryophyllaceae. 



Order 2. PORTULACEJ;. Calyx usually of 2 sepals and corolla of 

 5 petals: stamens usually 5, antipetalous : ovary usually trimerous 

 and uniiocular ; fruit a capsule. They are herbs with alternate or 

 opposite leaves ; the corolla is fugacious. 



The structure of the flower is essentially the same in this order as in the 

 Chenopodiales, with the addition of a calyx of two antero-posterior sepals. 



Portulaca oleracea, the Purslane, from Southern Europe, and other species 

 are cultivated as vegetables and as ornamental plants. Montia (Blinks) has an 

 irregular (apparently gamopetalous) corolla; it grows in ditches or in damp 

 places. In the genus Lewisia there are 4-8 sepals, 8-16 petals, and indefinite 

 stamens. 



Order 3. AIZOACEJ: (FicoiDE^;). Flowers with a simple perianth, 

 and usually indefinite stamens, the more external of which are 

 often transformed into petaloid staminodes : ovary multilocular, 

 sometimes inferior. 



This order has marked affinities with the Phytolaccacese and the Nyctaginaceae, 

 so that it is sometimes placed among the Monochlamydeaa ; but the occurrence 

 of forms with petaloid staminodes justifies the position in which it is here placed. 

 It is of special interest inasmuch as it well illustrates the evolution of the 

 dichlamydeous from the monochlamydeous type of flower, with multiplication 

 of the sporophylls and the gradual metamorphosis of the more external of them 

 into petaloid staminodes which are, in fact, primitive petals. 



Mesembryanthemum is the genus with an inferior ovary : it has fleshy leaves 

 and conspicuous flowers ; many species are cultivated ; it comes from South 

 Africa. 



Cohort IV. Parietales. Flowers cyclic, with calyx and corolla : 

 sepals free : stamens definite or indefinite : gyneeceum. of two or 

 more carpels : ovary unilocular, sometimes many-chambered, with 

 parietal placentation : seed with or without endosperm. 



Order 1. PAPAVEEACEJ:. Flowers usually actinomorphic, K2, 



