The Journal of Heredity 



Thus far experiments in cross-breed- 

 ing Daturas have been confined to 

 forms of Datura stramonium. Other 

 species of this genus occur in marked 

 color forms. They vary in the arma- 

 ture of their fruits and are equally 

 inviting for study, especially the Asiatic 

 Datura metel above described. The 

 latter has still another interesting 

 form-variation: its corollas as already 

 stated, are sometimes simple and 

 sometimes double. Simple and double 

 flowers of the purple-flowered form, 

 usually called D.fastuosa, -were collected 

 by the writer from a single plant in the 

 garden of Mrs. Augustus Saint Gau- 

 dens, at Coconut Grove, F'lorida. 

 Simple and double flowers are also 

 encountered in other sections of the 

 genus, including the Brugmansias or 

 tree-daturas of South America. 



Datura meteloides, an American spe- 

 cies used ceremonially by the Mexicans, 

 Zunis, and California Indians, occurs in 

 two marked color forms, one with white 

 and the other with pale blue or lilac- 

 colored corollas. In Figure 14 these 

 forms are shown together with their 

 characteristic nodding pods subtended 

 by an expansion of the persistent base 

 of the circumscissile calyx. Very closely 

 allied to this species is the "Downy 

 Thorn-Apple" {Datura innoxia Miller) 

 already referred to, an American plant 

 often confused with D. metel L., 

 but differing from that species in its 

 downy indument and its 10-toothed 

 instead of 5-toothed corolla. i- Another 

 form closely related to D. meteloides 

 and still more closely to D. innoxia, is 

 D. discolor, also with nodding fruit 

 and a 10-toothed corolla, but easily 

 distinguished from both of its allies 

 by its black seeds. The narcotic plant 

 called Ololiuhqui by the Aztecs was 

 undoubtedly a Datura of this section, 

 although it has l)een erroneously de- 

 scribcfl as a species of Convohiilus, 

 or IpomoL-a. Hernandez, in describing 

 it, uses nearK' the same expressions as 

 Acosta when he speaks of Datura metel, 

 comparing its trumpet-shaped flower 



to that of a Convolvulus and its seeds 

 to lentils. 



All the Daturas thus far described 

 produce an abundance of seeds. Few 

 of the tree-daturas, or Brugmansias 

 of South America, on the other hand, 

 are known to be fertile in cultivation. 

 They therefore present greater diffi- 

 culties as material for the study of 

 heredity. It is quite possible that in 

 their native habitats they are pollinated 

 by long-billed humming birds, and 

 those that bloom in the evening and 

 are fragrant during the night may like 

 other Solanaceae, attract nocturnal 

 moths allied to the Sphingidae with 

 proboscids long enough to reach the 

 nectar at the base of the filaments. 

 Lagerheim noticed that certain species 

 growing in Ecuador are cross-polli- 

 nated by a humming-bird belonging 

 to the genus Docimastcs having a bill 

 12 cm. long. This bird visits the long 

 pendulous blossoms apparently in quest 

 of small insects as well as of nectar. 

 Shorter-billed species rupture the cor- 

 olla tubes from without. The flowers 

 of the tree-daturas vary greatly in color 

 as well as in the form of the calyx. The 

 latter in some species is spathe-like and 

 pointed, in others notched or toothed 

 at the apex. It would be of great 

 interest to cross-pollinate the white- 

 flowered Datura arborea with the re- 

 cently described red-flowered D. rubella 

 which closely resembles it in form; and 

 the orange-flowered D. a urea or the 

 delicate pink D. mollis with the white- 

 flowered D. Candida. Crosses might 

 also be made between the Brazilian 

 D. suaveolens, which has coherent 

 anthers, a 5-toothed inflated calyx and 

 slender fusiform fruit with other species 

 having distinct anthers, spathe-like 

 acuminate calyces, and spheroid or oval 

 fruits. It would be equally interesting 

 to o])ser\e the effects of crossing Datura 

 saniiuinea or D. rosei, species with the 

 fruit en\eloix'd in a persistent husk-like 

 cahx, with other species like D. piltieri, 

 in which the cal>x is Cjuite deciduous. 



Figure 15 shows the flowers of four 



'^ Typical specimens of Datura innoxia Miller, called by the Aztecs Nacazcul, or Toloatzin, 

 were collected hv Dr. Kdward Palmer in I8Q8 in the vicinity of San Luis I'otosi, Mexico (No. 

 677). 



