Crataemespilus x canescens
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| ( JBPhipps ) JBPhipps |
Crataemespilus x canescens is one in 1990 first described, spontaneously created genus hybrids between the German loquat and a North American Weißdornart. It was found in a grove in Arkansas . The existence of only a few individuals was originally described as a new loquat species with relict distribution andnamed Mespilus canescens before its hybrid nature was recognized by genetic tests. He was then from his first to describe even the Nothogattung x Crataemespilus assigned.
description
Crataemespilus x canescens is a shrub that is around 2 to 5 meters tall . The bark of the trunks flakes in irregularly shaped stripes, in various pale shades. The twigs occasionally have a few straight thorns; when young they are tomentose and gray. The gray colored leaves are 2 to 4 centimeters long, narrowly elliptical to inverted, the leaf edge finely serrated towards the tip. The flowers appear in April and last about a week. The hermaphrodite, about 18 to 20 millimeters wide flowers are five-fold. The five petals are white, but turn slightly orange when dry. There are about 20 stamens . The fruits are red and round in shape.
Crataemespilus x canescens is not diploid like the German medlar , but has a triple set of chromosomes ( triploidy ). It spreads agamosperm , whereby the seed set is extremely small.
Distribution and location requirements
The only natural occurrence of Crataemespilus x canescens was discovered in 1970 and comprises 25 plants in a small deciduous forest of about 9 acres in Arkansas. The area is known as the Konecny Grove Natural Area and is privately owned but serviced by the Arkansas Natural Heritage Commission . The forest was surrounded by prairie that was converted to cultivated land. Crataemespilus x canescens grows there together with hawthorn species ( Crataegus spec.), The hackberry ( Celtis laevigata ), the red mulberry ( Morus rubra ) and with stinging bindweed species ( Smilax spec.). Cuttings are grown at the Missouri Botanical Garden .
Systematics
The clan was formally described in 1990 and initially assigned to the genus Mespilus as a new species. In 2007, phylogenomic investigations (investigations of the relationship based on the comparison of homologous DNA sequences) showed a close relationship between the two suspected Mespilus species and the hawthorn genus , according to which they would be coffin together with the species Crataegus brachyacantha . & Engelm. form a clade . Incongruences between the determined relationships between the nuclear genome and the independent genome of the chloroplasts suggested that Mespilus canescens must in reality be a hybrid, this is possible based on the morphological characteristics and has now been generally accepted. The second parent species is likely Crataegus brachyacantha , but this has not been proven with certainty. After checking, introduced, cultivated medlars, which would have made hybridization possible, were found in a woody stand near the only site.
Whether the clan is actually a genus bastard depends on the systematic position of the German medlar, the only species of the genus Mespilus , which is monotypical again after the hybrid nature of Crataemespilus x canescens has been discovered . This is maintained by most taxonomists as an independent genus, but some have included it in a broader genus Crataegus .
The Nothogattung x Crataemespilus comprises, in addition Crataemespilus x canescens two other species, including the often planted as ornamental tree Crataemespilus x grandiflora (Smith) Camus, a hybrid between the loquat and the two handles leagues hawthorn . In addition, as + exist Crataegomespilus called Simon-Louis ex Bellair Pfropfchimären that are unstable, however, in their characteristic attributes.
Individual evidence
- ↑ a b Kimberlie McCue: Mespilus canescens , Center for Plant Conservation, 2005, Weblink (accessed September 23, 2008)
- ↑ a b c d Eugenia YY Lo, Saša Stefanovič, Timothy A. Dickinson (2007): Molecular Reappraisal of Relationships Between Crataegus and Mespilus (Rosaceae, Pyreae) —Two Genera or One? Systematic Botany 32 (3): 596-616. doi: 10.1600 / 036364407782250562
- ↑ a b c James B. Phipps (2016): Studies in Mespilus, Crataegus, and × Crataemespilus (Rosaceae), I. differentiation of Mespilus and Crataegus, expansion of × Crataemespilus, with supplementary observations on differences between the Crataegus and Amelanchier clades. Phytotaxa 257 (3): 201-229. doi: 10.11646 / phytotaxa.257.3.1
Web links
- Mespilus Linnaeus in Flora of North America, by James B. Phipps (with description of Crataemespilus × canescens ).
Literature and Sources
- Kimberlie McCue: Mespilus canescens , Center for Plant Conservation, 2005, web link (accessed September 23, 2008)
- JB Phipps: Mespilus canescens a new Rosaceous endemic from Arkansas . Systematic Botany 15, pp. 26-32, 1990
- James B. Phipps (2016): Studies in Mespilus, Crataegus, and × Crataemespilus (Rosaceae), I. differentiation of Mespilus and Crataegus, expansion of × Crataemespilus, with supplementary observations on differences between the Crataegus and Amelanchier clades. Phytotaxa 257 (3): 201-229. doi: 10.11646 / phytotaxa.257.3.1