Deciduous Hollies
Late January to Early February
'Winterberry' (Ilex verticillata) is one of several deciduous hollies present in the Arboretum’s Marsh Area. These are part of the Elmore Holly Collection which is described in
detail - including a full list of the collection and a site map.
Although one usually thinks of hollies as being evergreen, a variety
of hollies lose their leaves each fall and provide a display of bright colored fruits at this time of year. 'Winterberry' is one of three native deciduous hollies found in East Tennessee - the others being
Carolina Holly (Ilex ambigua v. amigua) and Mountain Holly (Ilex
ambigua v. montana). Many culivars and hybrids using Winterberry have been developed including the four examples shown below that can be seen in the Marsh Area this winter.
Left: 'Winter Gold' (Ilex verticillata)
Right: 'Bonfire' (Ilex serrata x verticillata)
Left: 'Stop Light' (Ilex verticillata)
Right: 'Earlibright' (Ilex verticillata)
Tigertail Spruce (Picea polita or Picea torano)
Early February
A good example of a Tigertail Spruce is found in the Arboretum's Dwarf and Unusual Conifer Collection. It is endemic (restricted in distribution) to Japan. Branches of young trees are horizontal, but its common name comes from the pendulous branches of older trees that are said to resemble tiger tails. The stiff, green, sharp-tipped needles are borne on short woody, peg-like structures called pulvini. In winter Tigertail Spruce has conspicuous reddish buds at the end of its branches. Restrictions on importing Tigertail Spruce, Western Hemlock, and other conifers have been developed by Canada and several states to prevent further introduction of the Hemlock Wooly Adelgid, which has been devastating Eastern Hemlock forests.
The distinctive cones hang down, a characteristic that helps differentiate spruces from firs (Abies spp.) which have erect cones. The grayish-brown bark of Tigertail Spruce becomes deeply fissured in older trees. In Japan, this species has been used for lumber, paper pulp and ornamental purposes.
Virginia Pine (Pinus virginiana)
Early to Mid February
Virginia Pine (also known as Scrub Pine) is one of several native pines found along Arboretum trails. Its twisted, yellowish-green needles are borne in bundles of two, a characteristic that helps distinguish it from Shortleaf Pine which has straight needles in bundles of 2-3.
Virginia Pine is a pioneer species that becomes established in open areas created by fire or other disturbance. The presence of older Virginia Pines in many of the Arboretum’s deciduous forests indicates a history of abandonment of farmlands.
The seed cones, which require 2 years to mature, have scales with thickened ends bearing slender, stiff prickles. Trunks of older Virginia Pine retain many dead limb stubs below the canopy. The flaky bark is gray-brown to light brownish orange. Virginia pine may grow up to 70 ft in height.
Alders (Alnus spp.)
Mid February
As spring approaches, two species of alder along Scarboro Creek below the Visitors Center have come into bloom. The conspicuous male catkins first appeared late this fall, but only now are shedding pollen. The pistils of the female cones have just emerged during the warm weather of the last weeks.
The Seaside Alder (Alnus maritima) has an unusual distribution, being found on the Delmar Peninsula of Maryland and Delaware, in northern Georgia, and in Oklahoma. Recent studies suggest these disjunct (isolated) populations, left behind as the glaciers receded, have become distinct subspecies.
Our native Hazel Alder (Alnus serrulata) ranges throughout the Eastern U.S. and west to Indiana, Missouri, Oklahoma and Texas. The fruits are found as clusters of cone-like structures that remain attached to the shrub throughout the winter.
Alders are generally associated with habitats such as stream banks, pond edges, and other wetlands. These shrubs are among a group of woody plants that have root nodules with symbiotic nitrogen-fixing bacteria. These bacteria convert inorganic nitrogen from the atmosphere to a form that can be used by plants. Studies have shown that the increased availability of nitrogen from alders can result in increased growth of trees planted in the same stands. Such studies support the idea that this nitrogen-fixing association enables alders to invade disturbed areas deficient in nitrogen.
Cornelian Cherry Dogwood (Cornus mas)
Late February to Early March
A major research collection of Cornelian Cherry Dogwood cultivars is present along Arboretum Drive and behind the Juniper Garden and Conifer Collection. Cornelian Cherry Dogwood is a multi-stemmed, small tree or shrub native to Central and Southern Europe and Western Asia. The fruit, which matures in summer, is bright red and olive-shaped. In its native habitat the fruit is used for syrup and jams. This Dogwood is one of the earliest flowering trees at the Arboretum - the first blooms were evident in the collection this past week (February 17). The numerous, small yellow clusters of flowers appear before the leaves. The objective of the ongoing research study is to identify plants with exceptional ornamental value (flowering, fruiting, and form) that are hearty in this climate. The seeds for the collection were obtained from native trees in Rumania and Croatia.
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