122 PRESENT-DAY GARDENING 



used as wall creepers in the milder districts. They require 

 good, well-drained soil, plenty of sunshine to ripen the 

 wood, abundant moisture in summer, but very little in 

 winter. In sub-tropical countries they are popular garden- 

 plants. 



THUNBERGIA 



T. alata and its varieties, with stems 4 to 5 feet long, and 

 flowering profusely from July to October, are valuable for 

 outdoor cultivation treated as half-hardy annuals in 

 warm, sunny places ; they are also popular in the green- 

 house and stove. T. grandiflora, a strong-growing tropical 

 species with large racemes of pale blue flowers, and its var. 

 alba ; T. laurifolia^ very similar to T. grandiflora ; and 

 T. affinis, with purplish-violet flowers marked with yellow 

 throat, form a trio for the stove. Propagated by seeds or 

 cuttings. 



. TROP^EOLUM (see Plate XXIV) 



Nasturtium. A South American genus, chiefly in- 

 habiting the mountains. There are annual and perennial 

 species, some fibrous, others tuberous-rooted. The best 

 perennial sorts are T. Leichtlinii, orange flowers ; T. poly- 

 phyllum (see Plate XXIV), yellow flowers, tuberous-rooted ; 

 T. speciosum y bright scarlet flowers ; T. tuberosum, scarlet 

 and green flowers, with slender stems, 10 to 12 feet high, 

 not hardy in all soils. For covering arbours, &c., the tall- 

 growing annuals, T. Lobbianum, T. major, and T. peregrinum 

 (Canary Creeper), are very effective. Tropaeolums flower 

 with the greater freedom in poor soil ; in better soil they 

 make more vigorous growth, and continue in bloom much 

 later. They are also useful for greenhouse decoration. 



