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Natural and Artificial Selection

Darwin pointed to florists to support his theory that natural selection guides the evolution of new species. Among breeders, artificial selection determines which plants reproduce most, just as natural selection drives reproductive success in the wild.

leaf variations2
Darwin argued that florists select variation in breeding populations that seem good for the garden trade. Victorian florists looked for natural variations in the leaf colors of Geraniums, ivies, and rex begonia and then grew them vegetatively to keep the variation constant. Today’s hosta growers do the same since leaf variation in hostas is all the rage.

Variegated Pelargoniums
Hand colored lithograph of “Gold and Silver Tricolor” leaf variants in geraniums from The Floral World and Garden Guide (1877).

Rex begonia Rex begonia Rex begonia
Hand colored lithographs of rex begonia show a variety of leaf patterns. From Beautiful Leaved Plants by E. J. Lowe, 1861

Ivy title pageIvy Frontispiece Multi-colored ivy leaves.

Chromolith frontispiece & title page from Shirley Hibberd’s The Ivy, A Monograph, 2nd. edition, 1893.

flower variations
Breeders began producing flowering primroses from the alpine auricula primrose in an astonishing variety of colors in the 18th century. Their colors range from dramatic near-black and white to the showier yellow and crimson.
Color plates of  Auricula species from Weinmann’s Conspectus, 1735. (Taken from plate 209, from the rare book collection of the Missouri Botanical Garden)

Victorian flower breeding yielded dramatic color patterns such as picotee in cultivars of buttercups and camellias. A pictoee flower is one whose edge is of a different color than its base, as if the blossom has been hand-dipped in a contrasting color.
Camellia 'Carlotta Papudof'
Camellia ‘Carlotta Papudof’ f rom The Florist and Pomologist, 1863.

During the 1800s, demand for dahlias and chrysanthemums surged as flower growers began propagating more in a wide range of colors, sizes and shapes including the popular pompon shape shown here.
Dahlia superflua-Jane Louden Mixed Raununculus - Georg Dionysius Ehret Chrysanthemums - Walter Hood Fitch
Colored lithograph of dahlias by Jane Loudon, 1849. Reproduction of colored engraving of mixed ranunculus by Georg Dionysius Ehret, 1750. Colored lithograph of chrysanthemums by Walter Hood Fitch from The Florist and Pomologist, 1863.

Valet-Consoli regalis Darwin noted in Variation of Animals and Plants Under Domestication that “verbenas, carnations, dahlias, cineraries” and “annual larkspurs” come in a dizzying array of color variations and number of petals and sepals. All of these variations, he pointed out, were selected artificially by breeders for the floral trade.

Hand-colored etching and engraving of annual larkspur (Consolida species) by Pierre Vallet, 1623.

Next –Wildlife Diversity and Adaptation
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