Stemona 



( 361 ) 



Stems 



STEMONA. 



Stove climbui-8 (rd. Roxburghiacerc), with showy, 

 fictid flowers. Propagation, by cuttings and 

 suckers. Soil, light, rich loam. 

 Principal Species : 



to 6" long (sijns. glorios- 

 oides, Roxburghia glo- 



riosa, andlt. viridiHoru). 



Curtisii, sum., grn., br., 



pur. 

 tuberosa, Jy., grn.. Ivs. 4" 



STEMS. 



The stem may be defined as the ascending axis 

 of the plant, whose function it is to bear the leaves, 



from these general qualities, there are many minor 

 ones, which have all to be dealt with when deter- 

 mining the character of a stem ; these, however, 

 cannot be treated upon in a work of this scope. 



Apart from the bearing of the leaves, branches, 

 and flowers, the stem acts as a channel along 

 which the supply of nutriment drawn up by the 

 roots may pnss, both before elaboration by the 

 leaves and after. The woody cylinder is for the 

 most part of mechanical service only, the cam- 

 bium layer being the only living part : this applies 

 to old stems. 



STATICE RETICVLATA. (THE SMALL RADICAL LEAVES ARE HIDDEN BY THE 

 MASS OF ASPARAGUS-LIKE FLOWEIUXO BRANCHES ; see p. 360) 



branches, and flowers. It may be simple, i.e. un- 

 divided, as with most Palms." or be many times 

 forked, and carry a great head, of branches, as in 

 the case of large trees. The duration may bo 

 annual, as with all annual plants and most bien- 

 nials ; or perennial, as with trees and shrubs 

 generally. The structure may be herbaceous, i.e. 

 soft, and not woody, as with all herbaceous plants ; 

 or hard and woody, as with trees and shrubs gener- 

 ally. It may be erect, with short nodes (joints), 

 and capable of bearing its own weight and that 

 of its leaves and branches, or it may be compara- 

 tively thin and less rigid, although wiry, and 

 obtain support by climbing by one of the various 

 means of which plants avail themselves. Apart 



Stemonaeanthta (see Ituellia). 



Passing from the outside to the centre in the 

 transverse section of a young Dicotyledonous stem, 

 the zones of tissue passed through are (1) the 

 epidermis ; (2) the cortex, in which the vascular 

 bundles are embedded in a ring ; (3) the medul- 

 lary tissue or pith. In an old stem there would be 

 (1) the bark, outer; (2) the bark, inner; (3) the 

 ring of cambium, which is now continuous ; (4) 

 the wood ; (5) the much compressed remains of 

 the pith. The cambium layer is of the highest 

 importance, since it is by the growth and division 

 of its cells that the stem year by year increases in 

 thickness, a zone of wood being annually formed 

 to the inside and a zone of bark (phloem) to the 

 outside. Success in the operations of budding and 

 grafting depends upon the bringing together of 

 the respective cambium layers in stock and scion ; 



