Potato Onion 



( 230 ) 



Potentilla 



planting, which prevents light and air reaching the 

 bases of the plants and the surface of the soil ; 

 and by leaving infested plants to rot on the ground. 

 When the disease is established there is no cure. 

 If, however, Bordeaux Mixture, which see, is applied 

 to the surfaces of the leaves immediately the disease 

 makes its appearance in the form of downy patches, 

 its progress may be arrested. The liquid mixture 

 should be applied through a knapsack sprayer. 

 Sprayings should be made at intervals of three 

 weeks. Every diseased leaf, stem, and tuber should 

 be burned. (See PHYTOPHTHORA.) 



Potato Scab. This is encouraged by the presence 

 in the soil of an overabundance of sharp grit. It is 

 often caused by a fungus of which little or nothing 

 is known save that scabbed sets almost invariably 

 produce a similarly infested crop. This may be 

 prevented by soaking the tubers for one and a half 



soil, with the addition of sand for the Alpines. 

 The hybrids like a rich, well-manured soil. 



Principal Species. Hybrid, and Varieties : 



[NOTE. All hardy perennial herbs except where 

 otherwise stated.] 



alcheinilloides, 6", sum., 



wh. 



ambigua, 6", Je., yel. 

 argyrophylla, li' to 3', 



sura., yel., Ivs. silky. 

 atrosanguinea, crim. 



(*///?. atrosanguiuea). 

 fruticosa, 2' to 5', sum., 



hdy. shr., yel. 

 Friedrichseni, 2' to 3', 



sum., hdy. shr.,paleyel., 



hybrid. 



hopwoodiaua, li', Je., 

 pale yel., ro., hybrid. 



nepalensis, !', sum., 

 crim. (/. formosa). 



nana, 1', crim. 



pallida, pale red. 

 uitida, 3" to 6", sum., ro. 



alba, wh. 



atrorubens, rosy pur. 



grandinora, pk. 



rosea, ro. 

 Saxifraga, 4" to C", My., 



wh. 



POTATO UP-TO-DATE (see p. 229). 



or two hours in a solution of 1J oz. corrosive sub- 

 limate in 25 gallons of water. "All tubers treated 

 should be planted or burned, as they are poisonous. 



POTATO ONION. 



A variety of Allium Cepa, also known as the 

 Underground Onion. It produces no seed, but is 

 increased by bulbs formed beneath the soil. 

 Except in districts where ordinary Onions do not 

 succeed well, Potato Onions are seldom grown, and 

 their culture is largely confined to cottage gardens. 

 Plant the bulbs in February in the same way as 

 Shallots ; lift and harvest the crop in August. 

 The Potato Onions keep well, and are useful for 

 flavouring purposes. 



POTENTILLA. (CINQUEFOIL.) 



Description. A valuable genus of herbs or sub- 

 shrubs (prd. Rosacese), principally half-hardy 

 perennials and a few annuals. They generally 

 make good border plants, the hybrids being the 

 more valuable for this purpose, and a number of 

 the Alpine species make capital rock plants. 

 Propagation, by seeds or division. Common garden 



Potato, Sweet (see Batatas edulis). 



Other Species and Varieties : 



alba, 6", Mch., wh. 

 alpestris, 6" to 12", Jy., 



yel. (/. maculata). 

 Anserina, 6", Jy., yel. 



Silver Weed, 

 argentea, 6", Jy., yel. 

 aurea, 9" to 12", sum., 



yel. (.//. crocea). 

 ambigua, yel. (//. 



dubia). 



clusiaua, 6", Je., wh. 

 davurica, 1', hdy. shr., 



wh. (//. fruticosa var. 



davurica of some), 

 flagellaris, 2', Je., creep- 

 ing, yel. 

 Fragariastrum, 4", Mch., 



procumbent, wh. 

 gracilis, 1' to 2', Jy., yel. 

 grandinora, Je., yel. 

 hippia.ua, li', Jy., yel. 

 hirta, 1', sum., pale yel. 



(ii/n. pedata). 

 lanuginosa, 6" to 12", 



Jy., yel. 

 micraudra, 1' to 2', sum., 



hdy. shr., yel. 

 minima, 3", My., yel. 



multifiila, 6", Jy., yel. 

 nivalis, 3" to 6 , Jy., wh. 

 nivea, 1', Je., yel. 

 palustris, 2', Je., pur. 



(*//"*. Comarum and 



C. palustre). 

 parvifolia, Je., hlf-hdy. 



shr., yel. 

 peimsy 1 vaiiien , IV, Je., 



yel. (syn. missourica). 

 pyrenaica, 8" to 18", 



sum., yel. 

 recta, 1', sum., pale yel., 



several vars. 

 reptans, 4", Je., creeping, 



yel. 



flore pleno, double 

 flowers. 



variegata, variegated 

 Ivs. 



rupestris, 6" to 12", My., 



wh. 

 russelliana, 1', sum., so., 



hybrid. 

 Sibbaldia, 3" to 6", Jy., 



yel. (*y. Sibbaldia 



procumbens). 

 splendens, 6", Mch., wh. 



