+Laburnocytisus adamii

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+Laburnocytisus
Laburnocytisus close up.jpg
+Laburnocytisus adamii has flowers typical of both laburnum and broom
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Fabales
Family: Fabaceae
Subfamily: Faboideae
Tribe: Genisteae
Genus: +Laburnocytisus
Binomial name
+Laburnocytisus adamii
(Poit.) C.K.Schneid.
Cultivar

+Laburnocytisus 'Adamii'

+Laburnocytisus adamii (also known as Adam's laburnum or broom laburnum) is a horticultural curiosity; a small tree which is a graft-chimaera between two species, a laburnum, Laburnum anagyroides, and a broom, Chamaecytisus purpureus (syn. Cytisus purpureus), which bears some shoots typical of the one species, some of the other, and some which are a peculiar mixture of both "parents". This binomial name is written as if it were one species, but strictly speaking it is not one species but two. The plus sign (+) indicates its unusual origin. The plant can also be described by the formula Laburnum anagyroides + Chamaecytisus purpureus.

+Laburnocytisus adamii is a legume, a member of the pea family Faboideae (or Papilionaceae, formerly Leguminosae). Only one cultivar, 'Adamii' (formally designated as +Laburnocytisus 'Adamii'), is known to have arisen from this graft.

Appearance[edit]

Most of the tree's branches resemble the laburnum in their foliage, which has three leaflets (3-palmate) and 3–6 cm long, yet also with dense clusters of broom-like shoots, also with three leaflets, but only 1 cm long and a darker green. It flowers in late spring or early summer; some branches have long (20–30 cm) racemes of yellow laburnum flowers, while others produce dense clusters of purple broom flowers. Remarkably, most branches will also produce coppery-pink flowers on short (8–15 cm) racemes, which are midway between the two "parents"; the leaves on these shoots are also intermediate. In older specimens, the proportion of broom and mixed tissues tends to decline, and the laburnum to predominate. The tree grows to a height of 7 m (rarely 8 m) and is hardy to USDA plant hardiness zone 5 in northern Europe. It requires moderately fertile, moist but well-drained soil and should be grown in a sunny position to flower well.

Origin[edit]

The plant originated in the nursery of M. Adam near Paris in 1825, probably as an accident;[1] Chamaecytisus purpureus is normally a low-growing plant, and grafting it onto a straight trunk of a related species would be expected to create an attractive, semi-weeping standard.

In theory, other +Laburnocytisus could be developed in the same way but using different "parents".

Structure[edit]

A graft-chimaera is not a true hybrid but a mixture of cells, each with the genotype of one of its "parents"; it is a chimaera, created by grafting, in which the tissue of one plant grows within an outer envelope of the second plant. In the case of +Laburnocytisus adamii, laburnum forms the core, surrounded by the broom.[1] Such plants are often called "graft hybrids", but as they are not true hybrids the use of this term is now discouraged.

Other graft-chimaeras[edit]

+Crataegomespilus is a graft-chimera between hawthorn (Crataegus) and medlar (Mespilus) which arose in a similar manner. There are two distinct cultivars that have arisen from this graft: +Crataegomespilus 'Dardarii' and +Crataegomespilus 'Jules d'Asnieres'.[2]

References[edit]

  1. ^ a b Hillier's Manual of Trees & Shrubs 5th Edition (1984) 164.
  2. ^ RHS Plant Finder 2006–2007 20th Edition (2006) 202.

External links[edit]