''Cochliostema'' is a genus of plants with two species in the family

Commelinaceae Commelinaceae is a family of flowering plants. In less formal contexts, the group is referred to as the dayflower family or spiderwort family. It is one of five families in the order Commelinales and by far the largest of these with about 731 kno ...

(the spiderwort and dayflower family). The genus occurs from southern

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to southern

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Systematics

''Cochliostema'' is a member of the subtribe Dichorisandrinae of the tribe Tradescantieae of the flowering plant family Commelinaceae. Its closest relative in the Dichorisandrinae is '' Plowmanianthus'', followed by '' Geogenanthus''. All three genera share the possession of flower petals fringed with moniliform trichomes. Within ''Cochliostema'' there are two species: '' Cochliostema velutinum'' R.W.Read and '' Cochliostema odoratissimum'' Lemaire. '' Cochliostema jacobianum'', a 19th-century name thought to represent another species and still popular among horticulturists, is considered as part of the latter species.

Morphology

Rosette, typically unbranched herbs with somewhat succulent, strap-shaped leaves. In the wild, plants grow as

epiphytes An epiphyte is an organism that grows on the surface of a plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphytes grow are called phoroph ...

; however, terrestrial plants are found on or around tree falls suggesting that these ground-dwelling plants had been growing epiphytically. One species, ''Cochliostema odoratissimum'', is a tank-epiphyte, resembling certain bromeliads in this respect. This species also attains the greatest size for the genus, with its leaves reaching to 1 m in length, and plants sometimes reaching 2 m in height.

Flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

s are borne in large thyrses and are generally the largest (ca. 2.5 cm diam.), among the most fragrant, and arguably the most complex in the spiderwort family. They consist of 3

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coine ...

s, 3 blue to blue-violet and fringed petals, 3 stamens fused by their filaments in the upper half of the flower, and 3 carpels fused into a single trilocular pistil. The fused staminal structure has 3 spirally coiled anthers enveloped and concealed by petaloid extensions of the filaments of the two lateral stamens contributing to the 3-staminate structure. These structures, termed "cuculli", are narrowed into two distal hose-like extensions.

References

*Hardy CR, DW Stevenson (2000) Development of the flower, gametophytes, and floral vasculature in ''Cochliostema odoratissimum'' (Commelinaceae). ''Botanical Journal of the Linnean Society'' 134 (1): 131-157. *Hardy CR (2001) Systematics of ''Cochliostema'', ''Geogenanthus'', and an undescribed genus in the spiderwort family, Commelinaceae. Ph.D. Dissertation, Cornell University, Ithaca, NY, USA. {{Taxonbar, from=Q5139392 Commelinaceae Commelinales genera Epiphytes