|
(Last Modified On 6/6/2016)
|
|
Acceptance
:
Accepted
|
|
(Last Modified On 6/9/2016)
|
|
Description:
Plants to 400 mm high, forming diffuse tufts, somewhat trailing. Stems slightly flattened, rooting at aerial nodes, dichotomously branched. Leaves sword-shaped, 3–6 mm wide, fairly soft-textured. Flower clusters (1–)2 for flowering stem, nodding, (1–)2-flowered; spathes greenish-translucent becoming dry and torn above, ± 5 mm long, lightly lacerate, bracts similar but smaller. Flowers blue, pendent; tepals subequal, elliptic, 12–15 mm long. Filaments ± 2.5 mm long; anthers ± 4 mm long. Style obscurely 3-lobed. Capsules 3-lobed, ± 7 mm long. Seeds 1(–2) per locule, compressed-ellipsoid, with a deeply sunken chalaza (doughnut-shaped), with funicle forming a pale fleshy body, surface smooth, epidermal cells domed. Flowering time: mainly July and August.
|
|
South African Province:
Western Cape
|
|
Distribution and ecology:
restricted to the northern Cedarberg and Pakhuis Mtns in Western Cape; on sandstone slopes in light shade near streams or in shelter of rocks.
|
|
Diagnosis:
misunderstood by Weimarck who described the species but had only the type collection available to him and thought Aristea singularis was a creeping or even vine-like plant. The species is indeed singular in many ways. Plants have tufts of leaves at ground level but produce persistent aerial stolon-like stems that root at nodes some distance from the parent plant, a feature unique in Aristea and in a sense it is a trailing plant. The immature capsules led Weimarck to believe they were ovoid-spherical and many-seeded and hence to assume its closest relationships lay with his sections Euaristea (now sect. Cladocarpae) and Ancipites (both now subg. Eucapsulares). The flowering stems, produced from leaf clusters are slender, usually dichotomously branched and bear pendent flower clusters. A remarkable species, its affinities seem to be with subg. Aristea, some taxa of which also have flowering stems with a dichotomous branching pattern. The broadly 3-lobed capsules are not exactly like the narrowly 3-winged capsules of subg. Aristea. The capsules contain only two seeds per locule (or by reduction one), but unlike the tangentially flattened, lamellate seeds of other members of subg. Aristea, they are rounded and ± doughnut-shaped, with a depression at the chalazal end. More remarkable, the funicle is persistent and fleshy, forming an irregularly lobed body, possibly serving as an attractant for ants, which carry the seeds to their nests, later consuming the fleshy tissue.
|
|
General Notes:
pollen grains of Aristea singularis are moderate in size for the genus and monosulcate, with a broad, elliptic aperture, the assumed ancestral condition for Aristea. Such grains are typical of sect. Racemosae of subg. Aristea but in other features A. singularis exhibits little in common with the section, which includes tall, robust plants with several to many, upright branched stems. In its small size it better resembles sect. Aristea but pollen grains of that section differ in being much larger and have complex apertures, typically with three confluent narrow apertures and appearing trisulcate. Preliminary molecular studies show A. singularis is llied to species of sect. Racemosae but its several morphological differences merit placement in its own section. The short stigmatic lobes resemble those of sect. Racemosae, in which the style is apically notched, whereas the stigmatic lobes of sect. Aristea are broad, fan-like and deeply fringed.
|
|
|