Laburnum 152^3 



This species is variable in the wild state, three sub-species having been 

 established by Wettstein ; but Schneider only recognises the typical form and the 

 following variety : — 



1. Van Alschingeri, Reichenbach, Icon. Flor. Germ. xxii. 30 (1869). 



Cytisus Ahchingeri, Visiani, Fl. Dalmat. iii. 262 (1852). 



Lower lip of the calyx much longer than the upper lip, not approximately equal 

 in length as in the type. Leaflets greyer and more pubescent beneath. 



A considerable number of varieties have arisen in cultivation, the most important 

 of which are : — 



2. Var. quercifolium, Loudon. Leaflets, three or five, deeply lobed. 



3. Var. bullatum, Koch, Dendrologie, i. 17 (1869). Leaflets curled, and puckered 

 with swellings. 



4. Var. sessilifolium, Kirchner, Arb. Muse. 399 ( 1 864). Leaflets crowded, sessile. 



5. Var. aureum, Simon-Louis, Cat. 1880, p. 51 ; Van Houtte, Flore des Serres, 

 xxi. 2242, 2243 (1875). Foliage yellow. 



6. Var. pendulum, Koch, loc. cit. Branchlets pendulous. 



7. Var. Carlieri,"^ Kirchner, Arb. Muse. 398 (1864). Leaflets smaller than in 

 the type. Flowers small, in short, more or less erect racemes. 



Hybrids 

 L. vulgare is one of the parents in each of the following hybrids : — 

 \. Laburnum Watereri, Dippel, Laubholzkunde, iii. 673 (1893). 



Laburnum vulgare, vars. Watereri, intermedium, and Farksii, Kirchner, Arb. Muse. 399, 400 (1864). 

 Cytisus Watereri, Wettstein, in Oesterr. Bot. Zeitschrf. xli. 129 (1891). 



This is intermediate between L. vulgare and L. alpinum in the characters of 

 the branchlets, foliage, and pods, and in the time of flowering ; but it approaches the 

 former species in the colour of the flowers, and exceeds it in the length of the 

 racemes, which bear numerous flowers on long pedicels. The young branchlets, 

 petiole, and under surface of the leaflets, have a few scattered appressed hairs. 



This hybrid has been noticed in the wild state,^ as at Bozen in the Tyrol, where 

 Hausmann gathered it in 1856. It appears to have originated several times in 

 cultivation; and was first noticed in 1842, when it was offered for sale by T. D. 

 Parkes,^ a nurseryman at Dartford. He states that it was raised from seed, and had 

 flowers of a deeper colour than L. vulgare, borne in racemes 1 5 in. long. 



It afterwards appeared in a bed of seedlings in Waterer's nursery. Darwin* 

 found that 20 per cent of the pollen grains were ill-formed and useless, and that in 

 most seasons it yielded no fruit.* In 1865 his tree produced a few pods, some of 



1 Several plants appear to be known under this name, and possibly may be different forms, arising from the hybrid in the 

 second generation. 



2 Wettstein, in Oesterr. Bot. Zeitschrf. xli. 170 (1 89 1). ' Cf. Card. Chron. 1842, pp. 365 and 705. 



* Variation of Animals and Plants, i. 416 (1890). A shrub at Aldenham, named L. Alschingeri, agrees in foliage and 

 long racemes with L. Watereri ; but produces every year abundance of pods, which apparently contain good seed. Mr. 

 Vicary Gibbs raised seedlings from it some years ago. 



* Wettstein states that 42 per cent of the pollen grains are useless ; and in 1890 made the following observations on 

 three trees of similar age in the Vienna Botanic Garden : — L. vulgare bore 654 pods, with about 3000 seeds ; L. alpinum 

 produced 562 pods, with about 2500 seeds ; while L. Watereri bore only 7 pods, with 2 1 seeds, of which only 5 were fertile. 



