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The hardest hardwoods are much harder than any softwood, [4] but in both groups there is enormous variation with the range of wood hardness of the two groups overlapping. For example, balsa wood, which is a hardwood, is softer than most softwoods, whereas the longleaf pine, Douglas fir, and yew softwoods are much harder than several hardwoods.
Pines have four types of leaf: Seed leaves on seedlings are borne in a whorl of 4–24. Juvenile leaves, which follow immediately on seedlings and young plants, are 2–6 centimetres (3 ⁄ 4 – 2 + 1 ⁄ 4 inches) long, single, green or often blue-green, and arranged spirally on the shoot. These are produced for six months to five years ...
Sclerophyll plants are also found in areas with nutrient-poor and acidic soils, and soils with heavy concentrations of aluminum and other metals. Sclerophyll leaves transpire less and have a lower CO 2 uptake than malacophyllous or laurophyllous leaves. These lower transpiration rates may reduce the uptake of toxic ions and better provide for C ...
Pines with one fibrovascular bundle per leaf, (the former subgenera Strobus and Ducampopinus) were known as haploxylon pines, while pines with two fibrovascular bundles per leaf, (subgenus Pinus) were called diploxylon pines. Diploxylon pines tend to have harder timber and a larger amount of resin than the haploxylon pines.
Shortleaf pine is a source of wood pulp, plywood veneer, and lumber for a variety of uses. The shortleaf pine is one of the southern US "southern yellow pines"; it is also occasionally called southern yellow pine or the shortstraw pine. The wood from the shortleaf pine is used commercially for creating flooring and beams.
Leaf size varies from 2 mm in many scale-leaved species, up to 400 mm long in the needles of some pines (e.g. Apache pine, Pinus engelmannii). The stomata are in lines or patches on the leaves and can be closed when it is very dry or cold.
Leaves of most plants include a flat structure called the blade or lamina supported by a network of veins, a petiole and a leaf base; [1] but not all leaves are flat, some are cylindrical. [citation needed] Leaves may be simple, with a single leaf blade, or compound, with several leaflets.
The Pinaceae (/ p ɪ ˈ n eɪ s iː ˌ iː,-s i ˌ aɪ /), or pine family, are conifer trees or shrubs, including many of the well-known conifers of commercial importance such as cedars, firs, hemlocks, piñons, larches, pines and spruces. The family is included in the order Pinales, formerly known as Coniferales.