132 Floristik und Systematik der Phanerogamen. 



Willis, J[ohn] C[hristopher], A Revision of the Podostemaceae 

 of India and Ceylon. (Annais of the Royal Botanic 

 Gardens, Peradeniya. Vol. I. 1902. p. 181—250.) 



Having pointed out the insufficiency of Herbarium material 

 for the study of these difficult plants, the author gives a sum- 

 mary of the previous literature dealing with the Indian and 

 Ceylon species. 



The detailed investigations of the morphology and life- 

 history of the Indian species on which the present revision is 

 based will be clescribed in a forth-coming paper. A short sum- 

 mary of the principal characrers is given on p. 189 — 196. The 

 seeds germinate under water and the plant remains submerged 

 and purely vegetative until near the end of the wet season. The 

 primary axis is commonly insignificant and from its base arises 

 the „thallus" which may be morphologically a shoot or a root. 

 Secondary shoots arise endogenously from the thallus and these 

 ultimately bear the flowers which open above the water. The 

 primary axis is known in only a few of the Asiatic species. 

 The thallus, even in a Single species, is very variable in form 

 and in degree of attachment to the rock. The secondary shoots 

 are formed endogenously, in the root-thalli dose to the apex, 

 in the shoot-thalli of Lawla further back. The leaves are very 

 delicate and usuaily quite simple; in herbarium specimens they 

 are commonly missing or have lost their tips. The morphology 

 of the Spat he is obscure; it probably represents two or more 

 leaves united. The manner in which it opens to allow of the 

 emergence of the flower is of taxonomic importance. The 

 pedicel is non-existent before the opening of the spathe. It 

 sometimes attains a length of 5 — 6 mm between the opening oi 

 the spathe and the unfolding of the flower. It usuaily elongates 

 further while the fruit is ripening and at the same time the 

 outer cortical tissue falls away or shrivels and the central tissue 

 which remains becomes woody. The flowers are 3-merous, 

 regulär and with a perianth (§ Tristicheae) or without perianth, 

 2-merous and zygomorphic (§ Eupodostemeae). In many forms 

 the cortex of the ovary is deciduous with that of the pedicel. 

 The chief characters of the fruit, of taxonomic importance, are 

 the presence or absence of ribs and in the Eupodostemae, the 

 equality or inequality of the 2 lobes. The seeds are usuaily 

 very numerous, 2 — 4 only in Farmeria. 



In subdividing the Order (as distinct from the Hydro- 

 stachyaceae), the author adopts Tulasne's two main groups, the 

 Chlamydeae and the Achlamydeae distinguished mainly by the 

 presence or absence of perianth. The Chlamydeae are again 

 divided into the Tristicheae (3-merous) and the Weddellneae 

 (5-merous). The Achlamydeae may be arranged in a series of 

 groups of increasing flower -zygomorphism and the author 

 regards W arming's arrangement as the nearest approach to a 

 natural grouping at present possible. All the asiatic species 

 known belong to the Tristicheae and the Eupodostemeae. 



