Description:
Evergreen herbs with short to long rhizomes or aerial stolons (A. singularis). Stems rounded to compressed and 2-sided, then 2-angled or 2-winged, simple or few- to many-branched. Leaves sword-shaped to linear or terete, in two ranks, crowded basally, usually with a few progressively smaller leaves above; without marginal vein or subepidermal sclerenchyma, marginal epidermal cells thickened, columnar. Inflorescence simple or compound, composed of one or more binate rhipidia (flower-clusters in 2 series, unless reduced to 1 flower); lateral clusters stalked or sessile; spathes enclosing flowers green, rust-colored, or partly to entirely membranous or dry and papery, margins entire, irregularly torn, or fringed; floral bracts (within spathes) similar but usually smaller, forked apically, often 2-keeled. Flowers actinomorphic, upright or half to fully nodding, mostly fugaceous, lasting a single day (rarely 2 days), pedicellate or often subsessile, perianth twisting spirally on fading, persisting on ovary, usually dark blue, sometimes pale blue, white, mauve, or pink, occasionally with contrasting markings, scentless; with nectar from perigonal nectaries only in A. spiralis; tepals basally connate for 0.5–2.0(3.0) mm, subequal, or outer tepals shorter, always narrower than inner, oblanceolate to obovate, usually spreading horizontally, sometimes ascending. Stamens free; filaments filiform (unequal in A. inaequalis); anthers oblong to linear. Ovary top-shaped, triangular-columnar or oblong, with ovules opposite in 2 rows or alternating, forming a single row; style filiform, eccentric, either minutely 3-notched or divided into spreading, ± subentire or deeply fringed stigmatic lobes. Capsules ovoid to oblong or cylindric, rounded in section or shallowly to deeply 3-lobed, or broadly 3-winged, subsessile or stalked, remains of perianth persisting on developing capsule. Seeds rounded to angular (prismatic), shortly cylindric, triangular-columnar, or radially compressed and lamellate, with foveate sculpturing or smooth, many per locule or only 1 or 2. Pollen grains monosulcate, zonosulcate, trisulcate, spiraperturate, sometimes exine covering aperture, exine reticulate to microreticulate or rugose. Basic chromosome number x = 16.
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