The Laricoideae are a subfamily of the Pinaceae, a Pinophyta division family. They take their name from the genus Larix (larches), which contains inside most of the species of the group and is one of only two deciduous genera of the pines complex (together with Pseudolarix, which however belongs to a different subfamily, the Abietoideae). Ecologically important trees, the Laricoideae form pure or mixed forest associations often dominant in the ecosystems in which they are present, thanks also to their biological adaptations to natural disturbances, to reproductive strategies put in place and high average longevity of the individuals. Currently are assigned to this subfamily three genera (Larix, Pseudotsuga and Cathaya) and its members can be found only in Northern Hemisphere.[1] The various species live for the most part in temperate or cold climates and are the more northerly conifers; some constitute an important source of timber and non-timber forest products.
The species of the subfamily Laricoideae are evergreen or deciduous trees that can reach the greater heights in the Pinaceae family (over 100 meters with Pseudotsuga menziesii var. menziesii[2]). The leaves are needle-like[1] and have primary stomatal bands only on the abaxial surface (below the phloem vessels). All members are monoecious, with separate sexes on the same plant but in different reproductive structures. The annual cones (strobili) have no distinct umbo and the scales show a broad base which, at observation, completely hides the seeds from the abaxial view. These last are whitish and firmly fixed to the wing (this thin membrane also keeps the seed well attached to the scale during maturation); furthermore, among the typical distinctive features of the group, we have the micropylar fluid of the strobilus absent, no resin vesicles on the seeds[1] and the presence, in the vascular cylinder of the young root, of two characteristic small resiniferous canals. The bark and the wood of the genera Larix and Pseudotsuga have a similar anatomy and morphology: the reddish color of the heartwood and the white-yellowish of the sapwood, the high specific weight compared to other conifers, the distribution of late and earlywood, the presence of resiniferous channels and their localization in the tissuets, the molecules that form the resin and extractives, the chemical, physical and mechanical properties as well as the class of resistance to the attack of pathogens such as fungi and insects are a clue of a common ancestral origin. Similar between the two genera are also some aspects of the phenology, the degree of shade tolerance, the fire-resistant marbled bark and the appearance of the young shoots.[citation needed]
The subfamily Laricoideae was described with the actual name by Robert Knud Friedrich Pilger and Hans Melchior in late 1954[3] and subsequently modified by other authors in the course of time as regards the taxa of belonging. Before that, the genera Larix, Pseudotsuga and Cedrus were gathered in a provisional subfamily called Laricinae, defined for the first time by Melchior and Werdermann always in 1954 (...“trees that have both short and long shoots, monomorphic leaves, and strobili borne on the short shoots”...) and rechristened immediately after with the current term. The grouping in this form was confirmed by Hart (1987) through cladistic analysis, but already in 1988 Frankis replaced Cedrus with Cathaya (a genus described for the first time in 1962) in a new classification (now obsolete) that saw Larix as a distinct twin group compared to Cathaya - Pseudotsuga.[citation needed]