540 PART III. THE CLASSIFICATION OF PLANTS. 



ovary. These much reduced flowers are disposed in regular 

 order on the spadix : thus in Arum (Fig. 349) the numerous $ 

 flowers, consisting each of one carpel (Fig. 349/). y are inserted on 

 the base of the spadix ; and the <J flowers, each consisting merely 

 of 3-4 stamens, are closely packed higher up on it (Fig. 349 a). 

 The upper part of the spadix is covered with rudimentary flowers 

 (6, c). When, as in this case, the perianth of the true flowers is 

 wholly wanting, the whole inflorescence may assume the aspect 

 of a single flower; but irrespectively of the numerous intermediate 

 forms which are to be found, such a view is untenable when it is 

 borne in mind that here the ovaries are invariably situated below 

 the stamens, while in a flower they are invariably above them. 



The usually sympodial stem may be underground, a tuber, or a 

 rhizome, or it may be aerial ; in the latter case it often climbs, 

 clinging to trees by means of aerial roots. The leaves are either 

 alternate and distichous or, more often, spiral with a divergence 

 of f . They are rarely narrow, linear, or ensiform, and commonly 

 consist of leaf-base, petiole, and blade ; the venation is reticulate, 

 and the leaf often exhibits a more or less complicated segmenta- 

 tion. Laticiferous sacs or cells (see p. 141) occur in some families 

 of the order, as do also sclerotic cells (see p 133). 



Fam. 1. Pothoidea : without either laticiferous or sclerotic cells: flowers 

 usually $ , with or without a perianth. This family includes a number of 

 genera, such as Pothos, Anthurium, Acorus. The only member which occurs in 

 Britain is Acorus Calamus, the Sweet Flag, which grows on the margins of 

 ponds and rivers : its subterranean rhizome bears long ensiform alternate 

 leaves, crimped at the edges ; its flowering-shoot is triquetrous, bearing a 

 terminal spadix which is, however, displaced to one ,side by the spathe which 

 developes so as to form a continuation of the long axis of the flowering-shoot : 

 the spadix is densely covered with flowers (Fig. 348). 



Fam. 2. M onsteroidea : without laticiferous cells, but with sclerotic cells : 

 flowers $ , mostly without a perianth. Monstera deliciosa (sometimes called 

 Pliilodcndron pertusum), with perforated leaves, is commonly cultivated in hot- 

 houses : it comes from Mexico. Scindapsus. 



Fam. 3. Calloideee : with straight rows of laticiferous cells : flowers usually 

 $ , with or without a perianth : leaves never sagittate. No member is indi- 

 genous in Britain : Calla palustris occurs in the marshes of Northern Europe ; 

 it has a white spathe and parallel-veined leaves. Symplocarpus. Orontium. 



Fam. 4. Lasioidece: with straight rows of laticiferous cells : flowers mono- 

 or ambi-sporangiate, mostly without a perianth : leaves sagittate, often 

 segmented. This family includes a number of typical genera, of which Amor- 

 pbophallus is the most conspicuous. 



Fam. 5. Philodendroidece : with straight rows oi laticiferous cells : flowers 



