PAYSON—NORTH AMERICAN AQUILEGIA. 137 
The section Macroplectrae is confined to the Rocky Mountains of the United States 
and northern Mexico and contains such well-known ornamental plants as A. caerulea 
and A. chrysantha. In it we find an interesting mingling of what have been considered 
primitive as well as those thought of as modern characters. The erect flowers and 
the very long spurs are modern adaptations, while the large laminz and the more 
primitive colors (blue, white, or yellow) are characters persisting from ancestral 
types. It is not difficult to see why the color has remained light, since these plants 
are mostly pollinated by moths. The large lamine serve to make the flower more 
conspicuous, and it is for this reason undoubtedly that they have been retained. It 
seems that this section must be considered the most specialized and modern of the 
three and A. longissima the most highly developed of all the species of the genus. 
Hybridism is of common occurrence in this genus. Wherever two species are 
found growing together we may expect to find hybrids, even though the species 
belong to different sections. Mr. M. E. Jones has noticed and collected many hybrids 
between A. caerulea and A. flavescens where the species were growing together at 
Alta, Utah. A. caerulea alpina may be the result of such a cross, since the locality 
in which it was found is in a region where the ranges of A. caerulea and A. flavescens 
join. Probably it is because Aquilegiae are so variable and hybridize so readily 
that no two closely related species seem ever to grow together. For this reason, also, 
isolation may be thought of as being the chief factor in species production in this 
genus. 
The accompanying chart (pl. 8) represents the hypothetical course of development 
of the species of Aquilegia. The flowers are shown at about one-half natural size. 
It will be noticed that the succession of the figures downwards on the page represents 
in each group a progressive development in color and structure. At the same time 
the upper figures in every case are of more northern species than the lower, or else of 
alpine ones; that is, extension southward or to lower altitudes is coordinate with 
specialization in color and form. 
DESCRIPTIONS OF SPECIES WITH KEY. 
KEY TO THE SPECIES. 
Flowers nodding. 
Flowers blue or white; spurs hooked, less than 1.5 cm. long; lamine as long as 
the stamens. (CYRTOPLECTRAE.) 
Flowers blue and white. 
Stems 30 cm. tall or more. 
Flowers about 2 cm. long; native species..1. A. brevistyla. 
Flowers about 3.5 cm. long; introduced species..2. A. vulgaris. 
Stems 8 to 15 cm. tall, glabrous.............--- 3. A. saximontana. 
Flowers white. Plants more or less pubescent....-.- 4. A. laramiensis. 
EXPLANATION oF PLATE 8.—Figs. a and 6, representatives of the section Cyrtoplectrae in America. 
a, Aquilegia sazimontana, flowers blue, alt. 3,000 to 3,600 meters, Colorado; b, A. laramiensis, flowers white, 
alt. 2,100 meters, southern Wyoming. 
Figs. c, d, and ¢, representatives of the section Macroplectrae. c, A, jonesii, flowers blue, alpine, Mon- 
tana; d, A. pallens, flowers white, alt. 1,500 meters, Colorado; e, A. longissima, flowers yellow, mountains 
in northern Mexico, 
Figs. f, g, and h, representatives of the canadensis group of the Rhodanthae;/, A. lithophila, flowers yellow, 
eastern Utah; g, A. triternata, flowers red, Arizona; h, A. skinneri, flowers light red and greenish, Mexico. 
Figs. i,j, and k, representatives of the formosa group of the Rhodanthae. 7, A. flavescens, flowers yellow, 
higher altitudes, Montana; j, A. formosa, flowers red, low altitudes, from Oregon to Alaska; k, A. tracyi, 
flowers red, California. 
