Proteaceae
Trees [shrubs], terrestrial, unarmed, not clonal [clonal]; usually with 3-celled, biramose [simple] trichomes, sometimes also with glandular trichomes [glabrous]. Branches erect [prostrate]. Leaves persistent, alternate [opposite or whorled], simple [pinnate, bipinnate, or palmate]; stipules absent; petiolate [sessile]; blade papery [leathery], pinnatisect, bipinnatisect, or tripinnatisect, margins usually lobed [lobed and/or with marginal teeth]. Inflorescences terminal [axillary], simple or compound, racemelike or paniculate [racemose or capitate]; 1 bract present, scalelike, subtending paired flowers [absent]; bracteoles absent. Flowers usually bisexual [unisexual], zygomorphic [actinomorphic], pedicellate [sessile]; perianth and androecium hypogynous; tepals 4 [rarely 3 or 5], remaining loosely coherent except between dorsal tepals [distinct or connate], valvate; nectary usually present, 1[–4], fleshy [scalelike], crescentic [forming a ring, or distinct]; stamens 4 [rarely 3 or 5], opposite tepals, usually all fertile [1+ sterile]; filaments wholly [partly] adnate to tepals [free]; anthers basifixed, usually bilocular and tetrasporangiate [lateral anthers unilocular and bisporangiate]; pistil 1[or 2]-carpellate; ovary superior, 1-locular; placentation marginal [basal or apical]; style 1, distinct [vestigial], apex often functioning as pollen presenter; stigma 1; ovules [1 or]2[+], hemitropous [anatropous or orthotropous], bitegmic, crassinucellate. Fruits follicles [achenes, drupes, or drupelike], dehiscent [indehiscent]. Seeds [1 or]2[+], ovate-apiculate, winged [wingless].
Discussion
Genera 81, species ca. 1700 (1 in the flora): introduced; Mexico, West Indies, Central America, South America, s, e Asia (including Malesia), s Africa, Indian Ocean Islands (Madagascar), Pacific Islands (Fiji, Micronesia, New Caledonia, New Guinea, New Zealand, Sulawesi, Vanuatu), Australia (including Tasmania).
Some species of Proteaceae produce edible seeds that have high protein and oil content, the most notable of which are macadamia nuts (Macadamia integrifolia Maiden & Betche and M. tetraphylla L. A. S. Johnson and their hybrids). Some rainforest species have been used as sources of timber for fine woodworking, including the one species naturalized in North America. The woods of these taxa have a distinctive, unusual grain due to the tall, wide rays, which are often lustrous and/or strikingly colored. Some Proteaceae are commercially exploited by the cut-flower industry, and the total area planted with these crops in 2002 has been estimated to be 10,000 hectares (P. W. Crous et al. 2004).
Molecular phylogenetic analyses have resolved the relationships of Proteaceae. Proteaceae are sister to Platanaceae and this clade is, in turn, the sister group of Nelumbonaceae (D. E. Soltis et al. 2000). These three families constitute Proteales as circumscribed by the Angiosperm Phylogeny Group (2016). Proteales are one of multiple lineages that branch near the base of the “eudicot” clade.
Prior to 1993, the affinities of Proteaceae were poorly understood, and the family was placed in a diverse range of taxa in different classifications of the angiosperms. None of these systems anticipated the close phylogenetic relationships of Proteaceae to Nelumbonaceae and Platanaceae, probably because the only morphological synapomorphy that any of them share is the distinctive hair base found in Platanaceae and Proteaceae (R. J. Carpenter et al. 2005).
Selected References
None.