Adam’s laburnum as a heredity puzzle
Cytisus adami, a supposed graft hybrid, stayed a ‘strange puzzle’ because nurserymen’s testimony never quite satisfied botanists.
Source
The production of a physiological puzzle: how Cytisus adami confused and inspired a century's botanists, gardeners, and evolutionists
Inspect source passages
Adam’s laburnum as a heredity puzzle
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
In 1830 the Paris horticultural society announced Adam’s new cytisus.
In 1830, the newly-established Société d’Horticulture de Paris announced in its journal that a local nurseryman, Jean-Louis Adam (1777–1830), had produced a new variety of cytisus
Who produced it?
Jean-Louis Adam (1777–1830), had produced a new variety of cytisus. The tree, given the name Cytisus adami at the time but commonly referred to in Britain
What they did
The article follows Adam’s 1830 claim, Poiteau’s documentation, Romanes’ Kew experiment, and Darwin’s cultivation of the ‘quasi-hybrid’.
What they found
Graft hybrids promised commercial control and evidence on heredity. Few believed Adam, even when they granted his honesty. Darwin used the tree while remaining unsure it was a true graft mingling of races.
The limits
What it doesn't show
This is a history of one plant’s evidential career, not a modern genetic assay of +Laburnocytisus adamii.
Key terms
- Graft hybrid
- A supposed new variety produced by mingling rootstock and scion tissues rather than by sexual crossing.
- Cytisus adami
- Adam’s laburnum: yellow and purple flowers, claimed to come from a graft.
- Weismannism
- Late-century heredity theory Romanes hoped a large-scale repeat graft might test.
- Bizarria orange
- The other famous historical graft-hybrid example known in the nineteenth century.
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See its role on concept claims, tensions it is part of, placement history, and related discoveries.
Quiz yourself
Adam claimed the laburnum was produced by?
Common questions
What did Adam claim?
The tree came from a graft, not cross-pollination.
Why did it matter?
Graft hybrids would evidence non-sexual heredity and commercial control of variety.
Did elites believe him?
Generally no; Caspary said few had ever believed the testimony.
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