美国白蜡种名及分布图美国白蜡种名及分布图http:/plants.usda.gov/java/profile?symbol=FRAXI序号拉丁名称英文名称1Fraxinus anomalasingleleaf ash2Fraxinus berlandierianaMexican ash3Fraxinus carolinianaCarolina ash4Fraxinus chinensisChinese ash5Fraxinus cuspidatafragrant ash6Fraxinus dipetalaCalifornia ash7Fraxinus excelsiorEuropean ash8Fraxinus gooddingiiGooddings ash9Fraxinus greggiiGreggs ash10Fraxinus latifoliaOregon ash11Fraxinus mandshuricaManchurian ash12Fraxinus mariesiiMaries ash13Fraxinus nigrablack ash14Fraxinus ornusflowering ash15Fraxinus papillosaChihuahuan ash16Fraxinus pennsylvanicagreen ash17Fraxinus profundapumpkin ash18Fraxinus quadrangulatablue ash19Fraxinus texensisTexas ash20Fraxinus uhdeishamel ash21Fraxinus velutinavelvet ash树种介绍一、Fraxinus americana White AshFEATURES Form large shade tree usually maturing at about 70 tall by 70 wide, but can become much larger upright oval growth habit in youth, quickly maturing to a rounded growth habit without a central leader medium to rapid growth rate Culture full sun to partial sun prefers moist, well-drained, deep, slightly acidic soils in full sun, and is somewhat adaptable to various soils and soil pHs, but overall it is not overly urban tolerant (especially to soil compaction and drought), especially when compared to Green Ash cultivars are propagated primarily by cuttings grafted onto seedling rootstock, while the species form is easily propagated by seeds Olive Family, with several noteworthy diseases (leaf anthracnose, leaf spots, branch cankers, mycoplasma-induced decline and dieback) and pests (ash borer, oyster shell scale) abundantly available in ball and burlap form Foliage opposite leaves are pinnately compound, to 15“ long overall, medium to dark green on the uppersides of the leaflets, and silvery-white to light green underneath, casting a dense shade and a slightly bicolor effect in the breeze leaflets (usually seven, but can be five or nine) are ovate (wider than Green Ash) and usually entire on the margins rachis is stout and enlarged at its base, leaving a prominent crescent moon-shaped (U-shaped) leaf scar upon abscission fall color is often a progression from vivid yellow to orange, maroon, red, and finally burgandy or purple, usually beginning in late September and completely abscised by mid-October (some cultivars may proceed directly from green to the darker reddish colors) Flowers the species form is usually dioecious (having separate male and female trees), but most modern cultivars are seedless (being almost exclusively male selections) green to purple inflorescences in April are ornamentally insignificant Fruits on female trees of the species form, fruits are green changing to brown, in prolific clusters of samaras, with the winged seeds littering the ground or falling into gutters in Autumn modern cultivars are seedless, being predominantly male clones Twigs the thick, smooth, and very stout lenticeled stems are olive, changing to gray or brown with age leaf scars are distinctly U-shaped (with the U being upright), with a large brown pubescent lateral bud resting within each leaf scar, and a large flattened terminal bud at the end of each stout twig Trunk gray-brown bark is very smooth in youth, but becoming very deeply furrowed and ridged in just a few short years, with the ridges interlacing to form a diamondback pattern of 2“ thick bark at maturity quickly losing its central leader to yield several large upright to spreading main branches, for a very rounded growth habit ID Summary pinnately compound leaves usually have seven leaflets which are entire, in opposite fashion on the stout and thick stems, with leaf scars having a curved, dipping line across the top of the scar growth habit is tightly upright oval and sparsely branching in youth, becoming more rounded with age, with smooth bark in youth becoming a ridged and furrowed, subtlely ornamental, thick bark with age fall color transitions through shades of gold and red and often terminates as red-purple or maroon modern cultivars usually have male inflorescences and are always seedless USAGE :Function shade or specimen tree, possessing great symmetry and stateliness, especially in youth Texture medium texture in foliage and bold texture when bare thick density in foliage and average density when bare Assets brilliant transition of Autumn colors moderately quick growth, establishment, and shade bold-textured bark, stems, and outline in Winter symmetrically rounded shape at maturity Liabilities not especially urban tolerant (although often put into this situation) has the potential for numerous disease and pest problems, with the most serious usually being leaf anthracnose and wood borers dense shade with maturity leads to dead stem litter from the interior of the canopy and turf die-out underneath surface roots and basal trunk flare with age Habitat zones 3 to 9 native to the Eastern and Midwestern United States and Southern Canada SELECTI