Aristea

Aristea is a genus of evergreen, perennial and rhizomatous species of flowering plants in the family Iridaceae, first described in 1789. The plants can differ in height between about to up to 1½ m and grow from, often woody, rhizomes, short rootstocks, or corm-like bases. The iris-like leaves grow in clumps, tufts or with few together and from the heart of these upright and often flattened stems arise that carry clusters of briefly flowering six-merous, star-symmetrical, mostly blue but rarely purplish to whitish, saucer-shaped blooms, subtended by green to brown or papery sheaths. The genus is distributed in tropical and southern Africa, as well as Madagascar. The genus name is derived from the Greek word arista, meaning "awn". In 2026 a total of 58 species are recognised.

Aristea is a genus of evergreen, perennial and rhizomatous species of flowering plants in the family Iridaceae, first described in 1789. The plants can differ in height between about to up to 1½ m and grow from, often woody, rhizomes, short rootstocks, or corm-like bases. The iris-like leaves grow in clumps, tufts or with few together and from the heart of these upright and often flattened stems arise that carry clusters of briefly flowering six-merous, star-symmetrical, mostly blue but rarely purplish to whitish, saucer-shaped blooms, subtended by green to brown or papery sheaths. The genus is distributed in tropical and southern Africa, as well as Madagascar. The genus name is derived from the Greek word arista, meaning "awn". In 2026 a total of 58 species are recognised. Blousuurkanol species are evergreen, perennial plants with erect to creeping rhizomes or in case of Aristea singularis above-ground stolons. The stems can be simple or have few to many branches and are rounded or in cross-section have two sharp corners, ridges, or thin, flat extensions of tissue (or "wings") running along its sides. The leaves are flattened in a plane parallel to the main stem, cylindrical or needle-shaped, are set in two vertical rows mostly near the base of the stem, and get progressively smaller further up. The leaves lack a vein along the margins as well as a layer of hard, thick-walled, dead support-cells directly below the outer skin (epidermis), unlike some other Iridaceae genera. However, the leaves derive rigidity from thickened skin cells arranged in columns along their margins. The inflorescence consists of paired, fan-like flower clusters or paired single flowers that are seated or have a stalk, and are enclosed by two leafy or dry spaths, that many have a margin that is entire, irregularly torn or fringed. The bracts subtending the individual flowers are comparable to the spaths but mostly smaller, with a forked tip and often two keels. The scentless flowers are star-symmetrical except for the excentric style, upright to nodding, and are usually fresh for less than a day, in few species for two days.The perianth is usually dark blue, but in some species mauve, pink, light blue or white, sometimes with a diffently coloured honey guide. When the flower is spent, it twists into a spiral and remains attached. The flowers do not produce nectar with the exception of Aristea spiralis, that has nectar-producing glands on the perianth. The perianth consists of an outer and an inner whorl of three spreading tepals each, which are only merged at the base. The outer tepals may be equal in length as the inner or somewhat shorter, and are always somewhat narrower, and may sometimes be brown or almost black. The six stamens are free, with line-shaped filaments, topped by oblong to line-shaped yellow anthers. The stamens are equal except in Aristea inaequalis. The inferior ovary is oblong, three-sided and higher than wide, or top-shaped, and are topped by a line-shaped, excentric style that ends in three minute notches or spreading, entire or fringed lobes. Each of the three locules may contain only one or two, or many seeds. The seeds are rounded to angular, shortly cylindric, or flattened and winged. Seeds may be light to dark brown or dark red-brown. Cells contain 8 pairs of homologous chromosomes (2n=16). File:Aristea abyssinica Suvarna 1.jpg|Aristea abyssinica File:Aristea africana MB 3.jpg|Aristea africana Aristea alata File:Aristea anceps DU 1.jpg|Aristea anceps File:Aristea angolensis Manson 1.jpg|Aristea angolensis Aristea angustifolia File:Aristea bakeri Ross 1.jpg|Aristea bakeri Aristea bequaertii File:Aristea biflora Linkie 1.jpg|Aristea biflora File:Aristea bracteata Hoekstra 2.jpg|Aristea bracteata File:Aristea cantharophila Dupreez 1.jpg|Aristea cantharophila Aristea capitata File:Aristea cistiflora Leroux 2.jpg|Aristea cistiflora Aristea cladocarpa File:Aristea compressa Dupreez 1.jpg|Aristea compressa Aristea cuspidata File:Aristea dichotoma Dewaal 1.jpg|Aristea dichotoma Aristea djalonis File:Aristea ecklonii Vanberkel 1.jpg|Aristea ecklonii Aristea elliptica File:Aristea ensifolia Vanberkel 1.jpg|Aristea ensifolia Aristea farafangana Aristea fimbriata Aristea flexicaulis File:Aristea galpinii Precey 1.jpg|Aristea galpinii File:Aristea glauca Brunke 6.jpg|Aristea glauca Aristea goetzei Aristea grandis Aristea humbertii Aristea inaequalis File:Aristea juncifolia Brink 5.jpg|Aristea juncifolia Aristea kitchingii File:Aristea latifolia Vynbos 1.jpg|Aristea latifolia File:Aristea lugens Dupreez 1.jpg|Aristea lugens Aristea madagascariensis Aristea majubensis Aristea montana Aristea nana Aristea nigrescens Aristea nyikensis File:Aristea oligocephala Brunke 1.jpg|Aristea oligocephala Aristea palustris Aristea parviflora Aristea pauciflora Aristea platycaulis Aristea polycephala File:Aristea pusilla Gillespie 2.jpg|Aristea pusilla File:Aristea racemosa Brunke 2.jpg|Aristea racemosa Aristea ranomafana File:Aristea recisa Brunke 1.jpg|Aristea recisa File:Aristea rigidifolia Brink 2.jpg|Aristea rigidifolia Aristea rufobracteata Aristea rupicola Aristea schizolaena Aristea simplex Aristea singularis Aristea spiralis Aristea teretifolia Aristea torulosa Aristea zeyheri Goldblatt, P., Dold, A. P., Manning, J. C. 2005. "Three cryptic new species of Aristea (Iridaceae) from southern Africa". Bothalia 4:121-128. Goldblatt, P. John C. Manning and Roy E. Gereau. 2002. "Nomenclatural Clarification in Aristea Section Racemosae (Iridaceae) in the Cape Flora of South Africa" Novon, Vol. 12, No. 2 (Summer, 2002), pp. 190–195 W. Marais. 1987. "Notes on Aristea (Iridaceae) in East Africa". Kew Bulletin, Vol. 42, No. 4, p. 932

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