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Helichrysum lanceolatum
Helichrysum lanceolatum is a species of plant endemic to New Zealand,[3][4] commonly known as niniao.[5] DescriptionHelichrysum lanceolatum is a member of the daisy family (Asteraceae) which is the most widely distributed and successful flowering family of plants in the world.[6] H. lanceolatum is among a significant number of New Zealand Helichrysum species, nine of which are endemic to New Zealand.[4] Many of these species grow into shrubs or trees and are woody, thus being termed tree daisy.[7] The New Zealand endemic Helichrysum species are heterogeneous, meaning they are not uniform and have distinctive traits.[8]  .jpg) Helichrysum lanceolatum is a tangled, much branched, interlacing shrub, growing up to 3 m in height.[9] It has light brown bark with slightly grooved branches and alternate leaves.[5] Young branchlets are finely hairy[9] and evolve from dark brown to lighter brown with dark streaks as the wood thickens and ages.[10] The leaves are green/grey in colour and are pointed or rounded,[9] smaller on flowering branches,[11] and are arranged alternately along branches.[10] The upper surface of the leaf is smooth,[11] the tip is silver, and the underside is grey and downy.[9]  The flower heads consist of abundant clusters of very small, up to 1 cm diameter, creamy white, scented flower heads.[5] These can be confused with the furry galls induced by Cecidomyiidae larvae.[10] The composite or compound flowers,[7] resembling a single flower,[12] are made up of multiple small flowers bordered by rows of discreet bracts;[13] the whole structure termed a capitulum.[8] Morphological differences are strongly linked to habitat and soil substrate with much smaller leaves found on plants growing in full sun and in rocky soil.[14] VarietiesHelichrysum lanceolatum contains the following varieties:[3]
RangeNatural global rangeHelichrysum lanceolatum is endemic to New Zealand, so only occurs in Aotearoa/New Zealand.[15] The genus Helichrysum has 500–600 species in Africa, Madagascar, the Mediterranean basin, Macaronesia, western and central Asia, and India.[16] New Zealand rangeHelichrysum lanceolatum is found throughout New Zealand and is widespread.[5] It is termed morphologically variable, meaning it has differing forms depending on habitat and geographical location.[14] Its New Zealand range is from the Northland Peninsula to the south of the South Island from sea level to about 900m.[17] It is also found on Great Barrier Island[18] and the Chatham Islands.[19] HabitatHelichrysum lanceolatum grows well in dry soil[5] and prefers open, sunny aspects and rocky ground.[9] Historically thought to grow only in rocky habitats[20] it now appears to grow well in ecologically disturbed sites,[14] forest margins,[17] as well as dry and humid and open forest ecosystems[21] and coastal habitats.[22] It is one of several native shrubby understory species in pohutakawa/kānuka dominant forest on Great Barrier Island.[18] EcologyLife cycle/phenologyHelichrysum lancoelatum has composite flowers which encourages pollination.[7] Many flowers can be pollinated by a single visiting insect,[7] even though only 2–3 florets within a cluster of 8–12 are female.[5] Insects are attracted by nectar-secreting glands on the inner base of each single flower,[7] a strategy for mass pollination by a single insect visit.[7] Following successful fertilisation, flowers wither and drop off, allowing seeds to develop within achenes. Achenes are hard-shelled casings for a single seed[23] and are covered with fine, downy hairs that act as parachutes[7] aiding wind dispersal function.[24] Aaron Wilton's research in 1997 suggests that most native Helichrysum species are pollinated by a wide range of insects, though more research is needed on pollination or phenology of New Zealand Helichrysum species.[8] H. lanceolatum flowers from October to January[17] with seeds ripening in February[5] and fruit developing in December.[9] Diet and foragingHelichrysum lanceolatum prefers rocky soils and full sun[9] and grows well in dry soil and can tolerate low rainfall.[5] It is also one of many native shrubs within the coastal, mid-dune plant community, so can tolerate a sandy soil substrate.[22] Interestingly, a 2004 study showed the H. lanceolatum populations of Central Otago, a drastically modified environment, to be more susceptible to fire and drought, perhaps due to the sparse vegetation cover and disturbed ecology of the area.[25] While not unpalatable, a 2002 study showed Helichrysum lanceolatum to be less palatable to introduced ungulates than other native species.[26] Predators, parasites, and diseasesH. lanceolatum is a host plant to some species in the native gall fly family Cecidomyiidae, whose larvae induce a large gall on the developing flower head.[27] More research is needed to understand the relationship between these species. Other examples of moth species whose larvae feed on H. lanceolatum are the Pseudocoremia rudisata, and the Celama parvitis, a rare small moth, occurring in eastern and inland South Island shrublands whose larvae feed on the foliage of H. lanceolatum.[28] The larvae of another moth species, Helastia siris, may be associated with H. lanceolatum though more research is needed.[29] A subsequent study has highlighted the association between the moth species Helastia triphragma and H. lanceolatum on Ōtamahua/Quail Island in Whakaraupō/Lyttelton Harbour and suggests that increasing plantings of H. lanceolatum may help to keep populations of this moth stable and attract other native moths like Asterivora chatuidea.[30] Interesting facts
The Latin derivation for Helichrysum comes from the Greek word, helios, the sun; chrysos, gold[15] and lanecolatum, lance shaped; from the Latin lancea, light lance, spear.[15] The Māori name niniao means glowing as dawn.[5] H. lanceolatum has many historical synonyms and has been named both Helichrysum glomeratum and Helichrysum aggregatum, both describing the ball-shaped flower heads.[17] In New Zealand Flora Vol. 1, H.H Allan, 1982, recognised three varieties due to different growing habits, distribution, and leaf size and shape; Helichrysum glomeratum, and var lanceolatum and var majus. The species Helichrysum glomeratum var lanceolatum was soon found to already be named Helichrysum lanceolatum,[11] and var majus not specifically distinct from H. lanecolatum, thus Helichrysum lanceolatum remained the official scientific name.[11] A DNA sequencing study in 2007 of H. lanceolatum and Anaphalioides bellioides, previously Helichrysum bellioides,[31] showed intergeneric hybridisation (crossing of genes between two distinct species within the same genus), occurring between these endemic species.[32] Both species belong to the Gnaphieae tribe (Asteraceae family).[31] The study looked at species from two distant Banks Peninsula populations, at Gibraltar Rock in the southern Port Hills and Long Bay Road in the remote eastern bays;[32] the hybrids studied showed many distinctive traits, of particular note, serrated leaves, a trait of neither parent plant and they demonstrated lower fertility.[32] The hybrid species has been named Helichrysum purdiei.[33] Hybrids between Helichrysum lanceolatum and Ewartiothamnus sinclairii (Hook.f.) have also been reported.[32] The late botanist Tony Druce noted that plants from Paerutu (Surville Cliffs), in Te Paki Ecological District on the Northern most point of the North Island[34] might be a distinct species due to their trailing growth habit.[35] This population also has fewer side branches, and smaller leaves than other North Island populations.[14] Druce also identified a large round-leaved form from Hick's Bay and recognized this species as having distinctive characteristics.[2] More recent studies have shown little genetic variation between populations, but some variability between geographically distant populations.[36] References
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