PLANTS, GREENHOUSE. 



377 



PLUMS. 



from about 2 feet to 20 feet. The stems 

 of shrubs throw off an undergrowth at 

 their base, which develop into new stems 

 in time and produce flowers. The rose is 

 an example of the smaller kinds of shrubs, 

 the laurustinus of shrubs of intermediate 

 size, and the arbutus of shrubs of large 

 size. Between herbaceous and ligneous 

 plants is an intermediate link, consisting 

 of plants which partake partly of the 

 nature of each, but are dissimilar to each 

 in some respects. These are termed sub- 

 ligneous plants. The hard lower portions 

 ot the stems of these are lasting, and send 

 forth fresh shoots every year, but the 

 extremities of the shoots thus sent forth 

 perish year after year, and are again re- 

 newed when the plant makes fresh growth. 

 Among these may be named sage, rue, 

 and southernwood. The above comprises 

 all that the ordinary gardener need know 

 with respect to the general classification of 

 plants. 



Plants, Herbaceous. See Herba- 

 ceous Perennials. 



Plants, Nature of. 



Plants may be described as organic 

 bodies, composed of an outer bark or epi- 

 dermis, and an interior, consisting of an 

 irritable elastic cellular tissue, through 

 which the sap necessary for its support 

 rises from the root towards the upper part, 

 namely, the leaves and flowers. Each cell 

 forms a small closed vesicle, a complete 

 laboratory in itself, through whose mem- 

 branes the sap oozes by the process of 

 osmosis, which may be explained as the 

 tendency of fluids to become diffused 

 through a separating membrane when 

 placed in contact with it, and the action 

 produced by this tendency, which is a 

 pushing action or impulse : the cells stand 

 side by side filled with most different 

 matters, which never become intermixed 



Each of these cells extract from the con- 

 tantly passing current of sap those con- 

 stituents required for its own product ; and 

 when its allotted elaboration is completed, 

 they either are passed on again in a fluid 

 state, or reserved for the future needs of 

 some other part of the plant, or they are 

 used to repair or increase its own solidity. 

 Plants are thus possessed of a vital prin- 

 ciple, only differing in form and intensity 

 from that of animals. 



Plants, Perennial. See Herbaceous 

 Perennials. 



Plants, Propagation of. 



pagation of Plants. 



See Pro- 



Plants, Roots Of. See Roots of 

 Plants, what they are. 



Plants, Suitable for Shade. See 



Shade, Plants suitable for. 



Plants, TuberOUS. See Tuberous 

 Plants, Propagation of. 



Plumbago (nat. ord. Plumbagineae). 



A genus comprising eight or ten species 

 of plants, mostly perennial, some fitted 

 only for the greenhouse, and others hardy, 

 with flowers, blue, pink, white, or purple 

 in colour. The most noteworthy for green- 

 house culture and decoration is Plumbago 

 Capensis, an admirable pillar plant, 

 capable of being trained to the rafters of 

 a greenhouse. Its flowers are of a beautiful 

 pale blue colour, and in form are very like 

 those of the phlox. It thrives in a compost 

 of rich fibrous loam, sand and peat, and 

 is propagated by shoots from the base of 

 the plant, which have rooted in the sur- 

 rounding soil, or by cuttings, struck in fine 

 loam and sand, in gentle bottom heat. 



Plums. 



The following are 28 excellent varieties 



