Halgania Erecta

''Halgania'' is a genus of small shrubs in the family Boraginaceae. The genus comprises about 20 species that are endemic to Australia. ''Halgania'' is named for Emmanuel Halgan, a vice-admiral in the French Navy.

Features

''Halgania'' species are spreading to erect shrubs or subshrubs up to 1.2 m high. Leaves are simple, alternating along the stem and membranaceous or leathery. The leaf margin is entire or toothed to serrate and often revolute. Herbaceous stems and leaves can be glabrous but also covered with glandular hairs, simple or bifurcating (resembling cleats, "dolabriform") hairs. In some species, the surface is also covered with a viscose layer of exudates.

The flowers have a calyx of five more or less connected sepals. The 5-parted corolla is blue to violet, rarely white and flat or widely cup-shaped, similar to '' Solanum''-flowers. The five stamens have short filaments and long yellow to yellow-violet anthers. They are connected via intertwining hairs to an anther cone. The pollen sacs open into a central channel, through which the style later emerges. Dusty pollen is released through a pore made by beak-like appendage of the anthers through buzz pollination. Fruits are two- or four chambered dry drupes.

File:Halgania_andromedifolia_-_Flickr_-_Kevin_Thiele.jpg, ''Halgania andromedifolia''
File:Halgania_erecta_flowers.jpg, ''Halgania erecta''
File:Halgania solanacea - Flickr - Kevin Thiele.jpg, ''Halgania solanacea''

Systematics

''Halgania'' is a genus that only occurs in Australia, its sister group is still unknown. There are three clades in the genus. The ''H. andromedifolia''-clade (''H. andromedifolia'' and ''H. rigida'') occurs exclusively in Western Australia and the sepals are often conspicuously inqually sized. The anther appendage is short. Species of the ''H. anagalloides''-clade are the only ones to have dolabriform hairs, and they occur in all states of Australia. Their anther appendage is of variable size. The ''H. littoralis''-clade contains the type species of the genus. Its members have neither dolabriform hairs, nor inqually sized sepals, and always long anther appendages. All species of the ''H. littoralis''-clade occur in Western Australia or Northern Territory. Also four-chambered drupes only occur in this group.

Distribution

''Halgania'' species occur in all states of Australia. They grow in well-drained soils and sand in dry climates, except to the hyper-arid regions of the Nullarbor Plain. The species are also absent from temperate and tropical areas.

Selected species

*''Halgania anagalloides'' Endl.
*'' Halgania andromedifolia'' Behr & F.Muell. – Lavender halgania, smooth halgania
*'' Halgania argyrophylla'' Diels
*'' Halgania bebrana'' Oldfield & F.Muell.
*''Halgania brachrhyncha'' Peter G.Wilson
*''Halgania corymbosa'' Lindl.
*'' Halgania cyanea'' Lindl. – Rough halgania
*'' Halgania erecta'' Ewart & B.Rees
*''Halgania glabra'' J.M.Black
*''Halgania gustafsenii'' F.Muell.
*''Halgania integerrima'' Endl.
*''Halgania lavandulacea'' Endl. – Blue bush
*''Halgania littoralis'' Gaudich.
*'' Halgania preissiana'' Lehm.
*'' Halgania rigida'' S.Moore
*'' Halgania sericiflora'' Benth.
*'' Halgania solanacea'' F.Muell.

References

New South Wales Flora online: ''Halgania''FloraBase: the Western Australian Flora: ''Halgania''

Ehretioideae
Boraginaceae genera

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