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It is one of two general types of trees, the other being a conifer, a tree with needle-like or scale-like leaves and seeds borne in woody cones. [1] Broad-leaved trees are sometimes known as hardwoods. [2] Most deciduous trees are broad-leaved [3] but some are coniferous, like larches. [4]
The great majority of conifer genera and species are evergreen, retaining their leaves for several (2–40) years before falling, but unusual deciduous conifers occur in five genera (Larix, Pseudolarix, Glyptostrobus, Metasequoia and Taxodium), shedding their leaves in autumn and leafless through the winter.
In many species with spirally arranged leaves, such as Abies grandis (pictured), the leaf bases are twisted to present the leaves in a very flat plane for maximum light capture. 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 ).
Evergreen and deciduous species vary in a range of morphological and physiological characters. Generally, broad-leaved evergreen species have thicker leaves than deciduous species, with a larger volume of parenchyma and air spaces per unit leaf area. [4] They have larger leaf biomass per unit leaf area, and hence a lower specific leaf area ...
On young plants, the leaves are needle-like, becoming small and scale-like on mature plants of many genera; some genera and species retain needle-like leaves throughout their lives. [1] Old leaves are mostly not shed individually, but in small sprays of foliage ( cladoptosis ); [ 1 ] exceptions are leaves on the shoots that develop into branches.
Members of the family Pinaceae are trees (rarely shrubs) growing from 2 to 100 metres (7 to 300 feet) tall, mostly evergreen (except the deciduous Larix and Pseudolarix), resinous, monoecious, with subopposite or whorled branches, and spirally arranged, linear (needle-like) leaves. [3] The embryos of Pinaceae have three to 24 cotyledons.
Periods of leaf fall often coincide with seasons: winter in the case of cool-climate plants or the dry-season in the case of tropical plants, [19] however there are no deciduous species among tree-like monocotyledonous plants, e.g. palms, yuccas, and dracaenas. The hydrangea hirta is a deciduous woody shrub found in Japan. [citation needed]
Temperate deciduous forests are characterized by a variety of temperate deciduous tree species that vary based on region. [6] Most tree species present in temperate deciduous forests are broadleaf trees that lose their leaves in the fall, [8] though some coniferous trees such as pines (Pinus) are present in northern temperate deciduous forests. [6]