106 



THE DICTIONARY OF GARDENING, 



Pliormium continued. 



white. A beautiful, variegated-leaved plant, altogether smaller 

 and more elegant than P. tenax. (R. H. 1878, 56. 



P. Forsterianum (Forster's). A synonym of P. Cookianum. 



FIG. 124. PHORMIUM TENAX, showing Habit and detached Flower. 



' Zealand Flax. fl. yellow or red, 

 I. from 3ft. to 6ft. or more in 



P. tenax (tough).* Common New ; 

 but variable, 2in. long. August, 

 length, rigid, erect, dark green, with a narrow, reddish-brown 

 margin, and always split at the tip when old. 1798. The 

 hardier of the two species. See Fig. 124. (B. M. 3199.) The 

 following are some of the best forms : 



P. t. atro-purpureum (dark purple). I. wholly of a beautiful 

 purple, suffused with a reddish tinge. A handsome form, 

 differing from the type only in the colour of its leaves. 



P. t. nigro-plctum (black-spotted). I. deep green, about 2ft 

 long and Ifin. wide, narrowly edged with blackish-purple, the 

 edge becoming broader and more distinct on the base, where it 

 forms a conspicuous, zigzag line, elegantly spread out as the 

 plants become mature. A compact-growing form, much dwarfer 

 in habit than the type, and smaller also in the foliage. 



P. t. variegatum (variegated).* I. dark green, striped with rich 

 yellow and white, often 6ft. in length. New Zealand. A very 

 pretty, striped form of the common species. 



P. t. Veitchlanum (Veitch's). A fine form, with shorter and 

 narrower leaves, which are of a bright pea-green, and have broad 

 stripes of a creamy- white, extending the entire length of each leaf. 



FHORODON HTJMULI. This insect, known also 

 as the Hop Aphis, is frequently m6st destructive to the 

 Hop-plants, whore these are cultivated on a large scale; 

 but in gardens it does little harm, though occasionally 

 hurtful to Hops grown for ornamental purposes. It 

 belongs to the green group of Aphides, and the genus 

 differs very little from the other Green Plies in appear- 



Phorodon Hnmuli continued. 



ance. Many efforts have been made to combat this pest 

 in the Hop-gardens. One remedy is to wash the plants 

 thoroughly, with the help of a garden engine, with a solu- 

 tion of 31b. or 41b. of soft soap in 

 200 gallons of water, adding a 

 little infusion of coarse tobacco 

 to the solution if thought fit; 

 another is furnished by a newly- 

 discovered emulsion of petroleum, 

 which is said to be very effective. 

 In gardens, it is only necessary 

 to look occasionally to the young 

 shoots, and to crush the Aphides 

 before they become numerous. 



What is regarded by most 

 entomologists as a variety of 

 this insect (P. Humuli, var. 

 Mahaleb) occurs in gardens on 

 leaves of Plums, and also lives 

 on Sloes. Among the most use- 

 ful assistants in reducing the 

 ravages of these, as well as of 

 other Aphides, are the larvaa of 

 Ladybirds (Coccinella septem- 

 punctata, &c.), of Golden-eyed 

 Flies (Chrysopa) ; and of Hawk- 

 flies (Syrphuf). 



PHOSPHATES OF LIME. 



Chemical substances which con- 

 tain the elements calcium and 

 phosphorus, both of which are 

 found to be present in all 

 plants. The ash which remains 

 when the plants are burned 

 invariably contains them in 

 greater or less amount. Ex- 

 periments on plants which are 

 supplied with food of definite 

 and strictly-ascertained composi- 

 tion, have proved that when 

 either of these elements is with- 

 held, the plants remain small 

 and stunted, though the other 

 elements required in the food 

 are all supplied. On adding 

 the missing element to the food, 

 growth begins, and goes on in 

 a healthy way. But, though this 

 has been ascertained, there is still much uncertainty as 

 to the way in which each of these elements exerts its 

 beneficial action on plants. It is believed that calcium 

 is of use both in enabling plants to obtain the sulphur 

 and phosphorus that they require more readily in com- 

 bination with it (in sulphate of lime and Phosphates of 

 Lime) than these elements could be otherwise supplied 

 to them, and in combining with oxalic acid, which is 

 largely formed in growing tissues of plants, but is 

 hurtful to them in excess. The calcium unites with 

 this to form oxalate of lime, in the shape of small 

 crystals, called " raphides," which are very common in 

 the cells of many plants in some resembling bundles of 

 minute needles ; in others, in the form of cubes ; in 

 others, like balls, studded over with sharp points. 

 Oxalate of lime is harmless to plants. Phosphorus is 

 believed to be of value chiefly in helping to form proto- 

 plasm, and to transfer it from place to place, as 

 needed for growth in the plants. Phosphates are em- 

 ployed chiefly to supply phosphorus, and they are drawn 

 from the soil by the plants as they require it. There 

 are several Phosphates that contain calcium. They differ 

 from one another in the percentage of calcium that they 

 contain, and also in their solubility; but, for a discus- 

 sion of their composition and preparation, the reader 



