POLTGALA. 



248 



POLYPODIUM. 



here a small portion of tlie air is 

 divided from the rest, as shown at 

 F, where there are two dampers, 

 No. 1 acting horizontally, and No. 

 2 vertically. By means of No. 2 

 a perfect command is obtained over 

 the quantity of air supplied to the 

 fire, and borne away by the cease- 

 less currents flowing onwards from 

 beneath the floor of the house. The 

 water-trough is to be furnished 

 with a screen, extending in front and 

 over the hot air opening, so that 

 the escape of the latter into the 

 house will not fully take place till 

 it has passed over a considerable 

 portion of the surface of the water 

 in the trough." 



Polta'nthus. — See Pri'mula. 



Poly'gala. — PolygaJece. — Milk- 

 wort. — Very handsome greenhouse 

 shrubs, natives of the Cape of Good 

 Hope, which should be grown in a 

 compost of two-thirds peat, and 

 one-third of very sandy loam, or 

 equal parts of peat and sand, with 

 one-third of vegetable mould, may 

 be used. The plants should be 

 frequently watered ; but the water 

 should not be suffered to remain in 

 a stagnant state about the roots. 

 When it is wished to raise young 

 plants, the tips of the shoots should 

 be taken off about three inches long, 

 and struck in sand under a bell- 

 glass. All cuttings of the shrubby 

 Polygalas are very apt to damp off ; 

 and therefore the glasses should be 

 frequently taken off and wiped. 

 There are other kinds of Polygala, 

 natives cf Europe, which are her- 

 baceous perennials ; and others 

 which are natives of North Ame- 

 rica, some of which are annuals and 

 some perennials. All the herbaceous 

 Polygalas are hardy dwarf plants, 

 very suitable for rock -work ; and 

 they may be grown in any common 

 soil, though they prefer peat or very 

 sandy loam. Some of the kinds of 



Polygala are now included in the 

 genus Muraltia, the type of which 

 is P. Heisteria ; and others in the 

 genus Mundia, the type of which is 

 P. spinosa. 



PoLY'GONATUM. — SmilacecB, or 

 AsphocUlecB. — Solomon's Seal . — 

 Hardy perennial plants which re- 

 quire no other care than planting 

 in any common garden soil. They 

 will thrive either in exposed situa- 

 tions, or under the shade of trees, 

 but the flowers are generally largest 

 when the plants are grown in the 

 shade. They are sometimes in- 

 cluded in Convallaria. 



Polygo'num. -PoZy^roT^ece. — This 

 is a very extensive genus and em- 

 braces a great many very different 

 plants ; some of which are British 

 weeds, and others stove plants fi-om 

 the East Indies or New South Wales. 

 Some of the commonest kinds in 

 British gardens are the Buckwheat 

 {Polygonum Fagopyrum), the Gar- 

 den Persicaria {P. Persicaria), and 

 the Water-pepper (P. Hydropiper), 

 the beautiful pink flowers of which 

 are so ornamental in the ponds in 

 Kensington Gardens and other 

 places. Plants so various in their 

 nature require of course different 

 kinds of soil and situation ; but - 

 they will all grow in sandy loam, 

 and are generally of the easiest cul- 

 ture. 



PoLYPO^DiUM. — CryptogamiaFi- 

 lices. — An extensive genus of very 

 beautiful Ferns, some of which are 

 natives of Britain, and others are 

 exotic. All Fei-ns should be grown 

 in shady, damp places ; and the 

 hardy ones thrive most in a shrub- 

 bery under the drip of trees, where 

 few other plants will grow. The 

 exotic kinds should be grown in a 

 stove glazed with green glass ; and 

 the atmosphere should be kept 

 damp by water being frequently 

 poured on the floor and flues. 



