Ulmus crassifolia | |
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Ulmus crassifolia McKinney Falls State Park, Austin, Texas. | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Rosids |
Order: | Rosales |
Family: | Ulmaceae |
Genus: | Ulmus |
Subgenus: | U. subg. Oreoptelea |
Section: | U. sect. Chaetoptelea |
Species: | U. crassifolia |
Binomial name | |
Ulmus crassifolia | |
Natural range (Florida population excluded) | |
Synonyms | |
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Ulmus crassifoliaNutt., the Texas cedar elm or simply cedar elm, is a deciduous tree native to south-central North America, mainly in southern and eastern Texas, southern Oklahoma, Arkansas, and Louisiana, with small populations in western Mississippi, southwest Tennessee, and north-central Florida; [2] it also occurs in northeastern Mexico. [3] [4] It is the most common elm tree in Texas. The tree typically grows well in flat valley bottom areas referred to as cedar elm flats. Its Latin name refers to its comparatively thick (crassifoliate) leaves; [5] the common name cedar elm is derived from the trees' association with juniper trees, locally known as cedars. [6]
The cedar elm is a medium to large deciduous tree growing to 24–27 m tall with a rounded crown. The leaves are small, 2.5–5 cm long by 1.3–2 cm broad, with an oblique base, and distinguish it from Ulmus serotina with which it readily hybridizes in the wild. Leaf fall is late, often in early winter. The wind-pollinated apetalous perfect flowers are produced in the late summer or early fall; they are small and inconspicuous, with a reddish-purple color, and hang on slender stalks a third to a half inch long. The fruit is a small winged samara 8–10 mm long, downy on both surfaces at first, maturing quickly after the flowering in late fall. [7] [8] [9]
Cedar elm is susceptible to Dutch elm disease (DED), though less so than American elm, and moderately damaged by the elm leaf beetle Xanthogaleruca luteola . The tree also suffers from a vascular wilt, the symptoms often confused with those of DED.[ citation needed ]
Cedar elms are very susceptible to mistletoe. Mistletoe is a parasite that roots itself into the vascular system of the tree, thus stealing valuable nutrients and water. In some cases, if not removed, the parasite can be devastating to large sections of trees and even fatal. They create club-like branches that die out at the ends. These "club" branches create openings for future pests such as the elm beetles and carpenter ants. No treatments are known to be safe enough to kill mistletoe without killing the tree. Removing the mistletoe manually is not a guarantee, but it is the best-known method for control.[ citation needed ]
Cedar elms are known to be highly immune to Texas root rot caused by the fungus Phymatotrichopsis omnivora. Because of this, it is usually planted in regions where P. omnivora is prevalent, since the closely related lacebark elm is highly susceptible and easily killed by the fungus.
U. crassifolia is extremely rare in cultivation in Europe [9] and Australasia. [10] Specimens were supplied by the Späth nursery of Berlin from the late 19th century. [11] Henry (1913) and Bean (1988) note that it does not thrive in northern Europe, where the branchlets often die back. [9] [12] Three trees supplied by Späth to the Royal Botanic Garden Edinburgh in 1902 as U. crassifolia [13] may survive in Edinburgh, as it was the practice of the garden to distribute trees about the city (viz. the Wentworth elm). [14]
The US national champion, measuring 37 m high in 2001, grows in the Meeman-Shelby Forest State Park, Tennessee. [15]
Widely available
None known.
Ulmus rubra, the slippery elm, is a species of elm native to eastern North America. Other common names include red elm, gray elm, soft elm, moose elm, and Indian elm.
Ulmus davidiana var. japonica, the Japanese elm, is one of the larger and more graceful Asiatic elms, endemic to much of continental northeast Asia and Japan, where it grows in swamp forest on young alluvial soils, although much of this habitat has now been lost to intensive rice cultivation.
Ulmus castaneifoliaHemsley, the chestnut-leafed elm or multinerved elm, is a small deciduous tree found across much of China in broadleaved forests at elevations of 500–1,600 metres (1,600–5,200 ft).
Ulmus macrocarpaHance, the large-fruited elm, is a deciduous tree or large shrub endemic to the Far East excluding Japan. It is notable for its tolerance of drought and extreme cold and is the predominant vegetation on the dunes of the Khorchin sandy lands in the Jilin province of north-eastern China, making a small tree at the base of the dunes, and a shrub at the top.
Ulmus serotinaSarg., the September elm, is an autumn-flowering North American species of tree. It is uncommon beyond Tennessee; it is only very locally distributed through Illinois, Kentucky, Arkansas, Mississippi, Oklahoma, Alabama, and Georgia, and disjunct populations into Nuevo León, Mexico. It grows predominantly on limestone bluffs and along streams to elevations of 400 m.
The field elm cultivar Ulmus minor 'Stricta', known as Cornish elm, was commonly found in South West England, Brittany, and south-west Ireland, until the arrival of Dutch elm disease in the late 1960s. The origin of Cornish elm in the south-west of Britain remains a matter of contention. It is commonly assumed to have been introduced from Brittany. It is also considered possible that the tree may have survived the ice ages on lands to the south of Cornwall long since lost to the sea. Henry thought it "probably native in the south of Ireland". Dr Max Coleman of Royal Botanic Garden Edinburgh, arguing in his 2002 paper on British elms that there was no clear distinction between species and subspecies, suggested that known or suspected clones of Ulmus minor, once cultivated and named, should be treated as cultivars, preferred the designation U. minor 'Stricta' to Ulmus minor var. stricta. The DNA of 'Stricta' has been investigated and the cultivar is now known to be a clone.
The Wych Elm cultivar Ulmus glabra 'Cornuta', in cultivation before 1845 – Fontaine (1968) gives its provenance as France, 1835 – is a little-known tree, finally identified as a cultivar of U. glabra by Boom in Nederlandse Dendrologie 1: 157, 1959.
The putative hybrid cultivar Ulmus × hollandica 'Serpentina' is an elm of unknown provenance and doubtful status. Henry identified it as intermediate between U. glabra and U. minor, a view accepted by Bean and by Melville, who believed that the specimens at Kew bearing the name 'Serpentina' were U. glabra "introgressed by U. carpinifolia" [: U. minor] and were similar to but "distinct from 'Camperdownii'".
The elm cultivar Ulmus 'Koopmannii' was cloned from a specimen raised from seed sent from Margilan, Turkestan by Koopmann to the Botanischer Garten Berlin c. 1880. Noted in 1881 as a 'new elm', it was later listed by the Späth nursery, catalogue no. 62, p. 6. 101, 1885, as Ulmus Koopmannii, and later by Krüssmann in 1962 as a cultivar of U. minor. Margilan is beyond the main range of Ulmus minor. Augustine Henry, who saw the specimens in Berlin and Kew, believed Koopmann's Elm to be a form of Ulmus pumila, a view not shared by Rehder of the Arbold Arboretum. Ascherson & Graebner said the tree produced 'very numerous root shoots', which suggests it may be a cultivar of U. minor. Until DNA analysis can confirm its origin, the cultivar is now treated as Ulmus 'Koopmannii'.
The Elm cultivar Ulmus 'Tiliaefolia' was first mentioned by Host in Flora Austriaca (1827), as Ulmus tiliaefolia [:linden-leaved]. The Späth nursery of Berlin distributed a 'Tiliaefolia' from the late 19th century to the 1930s as neither an U. montana hybrid nor a field elm cultivar, but simply as Ulmus tiliaefolia, suggesting uncertainty about its status. Herbarium specimens appear to show two clones, one smaller-leaved and classified as a field elm cultivar, the other larger-leaved.
Ulmus 'Louis van Houtte' is believed to have been first cultivated in Ghent, Belgium circa 1863. It was first mentioned by Franz Deegen in 1886. It was once thought a cultivar of English Elm Ulmus minor 'Atinia', though this derivation has long been questioned; W. J. Bean called it "an elm of uncertain status". Its dissimilarity from the type and its Belgian provenance make the 'Atinia' attribution unlikely. Fontaine (1968) considered it probably a form of U. × hollandica.
The hybrid elm cultivar Ulmus × hollandica 'Superba' is one of a number of intermediate forms arising from the crossing of the Wych Elm U. glabra with a variety of Field Elm U. minor. Boulger tentatively (1881) and Green more confidently (1964) equated it with a hybrid elm cultivated in the UK by Masters at Canterbury in the early 19th century, known as "Masters' Canterbury Seedling" or simply the Canterbury Elm. Loudon examined a specimen sent by Masters and considered it a hybrid, calling it U. montana glabra major.
The Field Elm cultivar Ulmus minor 'Viminalis Pulverulenta' (:'powdery'), also known as 'Viminalis Variegata', a variegated form of U. minor 'Viminalis', was first mentioned by Dieck, in 1885 as U. scabra viminalis pulverulentaHort., but without description. Nursery, arboretum, and herbarium specimens confirm that this cultivar was sometimes regarded as synonymous with U. minor 'Viminalis Marginata', first listed in 1864, which is variegated mostly on the leaf margin. It is likely, however, that 'Pulverulenta' was the U. 'Viminalis Variegata', Variegated Twiggy-branched elm, that was listed and described by John Frederick Wood, F.H.S., in The Midland Florist and Suburban Horticulturist 1847 and 1851, pre-dating both Kirchner and Dieck. Wood did not specify the nature of the variegation.
The Field Elm cultivar Ulmus minor 'Umbraculifera Gracilis' was obtained as a sport of 'Umbraculifera' by the Späth nursery of Berlin c.1897. It was marketed by the Späth nursery in the early 20th century, and by the Hesse Nursery of Weener, Germany, in the 1930s.
Ulmus bergmanniana var. lasiophyllaC. K. Schneid. is endemic to China, on mountain slopes at elevations of 2100–2900 m in Gansu, Shaanxi, north-west Sichuan, south-east Xizang, and north-west Yunnan.
The Siberian elm cultivar Ulmus pumila 'Pinnato-ramosa' was raised by Georg Dieck, as Ulmus pinnato-ramosa, at the National Arboretum, Zöschen, Germany, from seed collected for him circa 1890 in the Ili valley, Turkestan by the lawyer and amateur naturalist Vladislav E. Niedzwiecki while in exile there. Litvinov (1908) treated it as a variety of Siberian elm, U. pumilavar.arborea but this taxon was ultimately rejected by Green, who sank the tree as a cultivar: "in modern terms, it does not warrant recognition at this rank but is a variant of U. pumila maintained and known only in cultivation, and therefore best treated as a cultivar". Herbarium specimens confirm that trees in cultivation in the 20th century as U. pumilaL. var. arboreaLitv. were no different from 'Pinnato-ramosa'.
The Field Elm cultivar Ulmus minor 'Rugosa' was distributed by the Späth nursery, Berlin, in the 1890s and early 1900s as U. campestris rugosaKirchner. Kirchner's tree, like Späth's a level-branched suberose field elm, was received from Belgium in 1864 as Ulmus rugosa pendula. Kirchner stressed that it was different from Loudon's Ulmus montana var. rugosa, being "more likely to belong to U. campestris or its subspecies, the Cork-elm".
Ulmus parvifolia, commonly known as the Chinese elm or lacebark elm, is a species native to eastern Asia, including China, India, Japan, Korea, and Vietnam. It has been described as "one of the most splendid elms, having the poise of a graceful Nothofagus".
The elm cultivar Ulmus 'Turkestanica' was first described by Regel as U. turkestanica in Dieck, Hauptcat. Baumschul. Zöschen (1883) and in Gartenflora (1884). Regel himself stressed that "U. turkestanica was only a preliminary name given by me; I regard this as a form of U. suberosa" [:U. minor ]. Litvinov considered U. turkestanicaRegel a variety of his U. densa, adding that its fruits were "like those of U. foliaceaGilibert" [:U. minor].
The Wych Elm cultivar Ulmus glabra 'Gigantea' was listed as U. montana var. giganteaHort. by Kirchner (1864). An U. montana gigantea was distributed by the Späth nursery, Berlin, in the 1890s and early 1900s. It did not appear in Späth's 1903 catalogue. A specimen at Kew was judged by Henry to be "not distinct enough to deserve a special name". Both Späth and the Hesse Nursery of Weener, Germany, supplied it in the 1930s.