The genus Helichrysum consists of an estimated 600 species of in the sunflower family (Asteraceae). The type species is Helichrysum orientale. They often go by the names everlasting, immortelle, and strawflower. The name is derived from the Ancient Greek words ἥλιος (helios, sun) and χρῡσός (chrysos, gold).
It occurs in Africa (with 244 species in South Africa), Madagascar, Australasia and Eurasia. The plants may be annual plant, herbaceous perennial plant or , growing to a height of . The genus was a wastebasket taxon, and many of its members have been reclassified in smaller genera, most notably the Everlastings, now in the genus Xerochrysum.
Their leaf are oblong to lanceolate. They are flat and pubescent on both sides. The bristles of the pappus are scabrous, barbellate, or plumose.
The receptacle ( base of the flower head) is often smooth, with a fringed margin, or honey-combed, and resemble daisies. They may be in almost all colors, except blue. There are many inflorescence and generally flat-topped panicle or . The corolla lobes show glandular hairs at the abaxial surface.
Helichrysum species are used as food plants by the of some Lepidoptera species including the Bucculatricidae leaf-miners Bucculatrix gnaphaliella (which feeds exclusively on Helichrysum arenarium) and Bucculatrix helichrysella (feeds exclusively on H. italicum) and the Coleophora case-bearers C. caelebipennella, C. gnaphalii (feeds exclusively on H arenarium) and C. helichrysiella (feeds exclusively on H. italicum).
Species
Hilliard (1983) divided this large and heterogeneous genus in 30 morphological groups. But the genus remains controversial and is considered by many to be an artificial genus. The taxonomy of this large polymorphic and probably
polyphyletic genus is complex and not yet satisfactorily resolved. Several Australian species, such as
H. acuminatum and
H. bracteatum, have been reclassified in the genus
Xerochrysum in 1991, resp. as
X. subundulatum and
X. bracteatum. In 1989, misaligned species of
Helichrysum were reclassified in
Syncarpha. Species included in
Pseudognaphalium,
Anaphalis,
Achyrocline and
Humeocline are probably congeneric with
Helichrysum.
[Galbany-Casals, M. et al. 2014 Taxon, 63:608-624. Phylogenetic relationships in Helichrysum (Compositae: Gnaphalieae) and related genera: Incongruence between nuclear and plastid phylogenies, biogeographic and morphological patterns, and implications for generic delimitation] Australian species have also been reclassified to the genus
Chrysocephalum, including
Chrysocephalum semipapposum and
Chrysocephalum apiculatum.
[Wilson, P.G. (2016). "A taxonomic treatment of Chrysocephalum apiculatum and C. semipapposum (Asteraceae: Gnaphaliae)". Nuytsia. 27: 33–73. Retrieved 25 November 2020]
Uses
Several species are grown as
, and for dried flowers. When cut young and dried, the open flowers and stalks preserve their colour and shape for long periods.
Helichrysum italicum (synonym Helichrysum angustifolium) is steam distilled to produce a yellow-reddish essential oil popular in fragrance for its unique scent, best described as herbaceous, sweet, and honey-like. The epithet angustifolium means narrow leaved. It is commonly misspelled as augustifolium.[http://www.floralimages.co.uk/info/botanicallatin.html for more details on botanical naming.]
Gallery
File:Helichrysum moeserianum 2.jpg| Helichrysum moeserianum in De Hoop N.R., South Africa
File:Helichrysum orientale 2.JPG| Helichrysum orientale
File:Starr 070621-7414 Helichrysum petiolare.jpg| Helichrysum petiolare, Licorice Plant
File:Strawflower.jpg| Helichrysum roseo-niveum in Namibia
File:Helichrysum setosum.jpg| Helichrysum setosum
File:Helichrysumthianschanicumicicles.jpg| Helichrysum thianschanicum 'Icicles' on display at the San Diego County Fair, CA, USA
File:Starr 080117-2067 Helichrysum thianschanicum.jpg| Helichrysum thianschanicum (Icicles leaves) at nursery on Maui
File:Helichrysum umbraculigerum.jpg| Helichrysum umbraculigerum
Further reading
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HILLIARD, O. 1983. Flora of Southern Africa, Part 7 Inuleae, Fascicle 2 Gnaphaliinae. Government Printer, Pretoria, South Africa.
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WILSON, P.G. 1992c. The classification of some Australian species currently included in Helipterum and Helichrysum (Asteraceae: Gnaphalieae): part 3 Anemocarpa and Argentipallium, two new genera from Australia. Nuytsia 8: 447–460.
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Mesfin Tadesse & Reilly, T. 1995. 17. A contribution to studies on Helichrysum (Compositae - Gnaphalieae) - a revision of the species of north-east tropical Africa. In: Advances in Compositae Systematics (eds. D.J.H. Hind, C. Jeffrey & G.V. Pope). Royal Botanic Gardens, Kew, pp. 379–450.
External links
