Xerochrysum boreale Paul G.Wilson

Collins, Timothy L., Schmidt-Lebuhn, Alexander N., Andrew, Rose L., Telford, Ian R. H. & Bruhl, Jeremy J., 2022, There’s gold in them thar hills! Morphology and molecules delimit species in Xerochrysum (Asteraceae; Gnaphalieae) and reveal many new taxa, Australian Systematic Botany 35 (2), pp. 120-185 : 150

Xerochrysum boreale Paul G.Wilson , Nuytsia 28: 17 (2017)

Type: Port Keats opposite Dorcherty Island , Northern Territory, 9 Aug. 1983, C.R. Dunlop 6459 & G. Wightman (holo: DNA D0021944!; iso: AD 98419226 , BRI, CANB 345434 *, MEL 0291510 , NSW 518497 !) .

Xerochrysum bracteatum subsp. (Port Keats C. Dunlop + 6459), A. E. Holland in P. D. Bostock and A. E. Holland (eds), Census Queensl. Fl. 32 (2007).

Xerochrysum bracteatum subsp. Port Keats (C. Dunlop + 6459) Qld Herbarium, CHAH, Austral. Pl. Census (2020) [accessed 20 February 2020].

Erect, annual or perennial, taprooted herb. Stems and branches cobwebby or pilose, internode length 5–30 mm. Basal leaf rosette present in first year at flowering, later absent. Basal leaves oblanceolate to obovate, 30–70 mm long and 5–12 mm wide, base amplexicaul, margin cobwebby or pilose with septate trichomes, apex mucronate; abaxial indumentum hirsute with septate trichomes and with glands, midvein indumentum cobwebby or hirsute with septate trichomes; adaxial indumentum hirsute with septate trichomes. Cauline leaves oblanceolate, 20–80 mm long and 4–9 mm wide, base amplexicaul, margin cobwebby or hirsute with septate trichomes, apex mucronate; abaxial indumentum hirsute with septate trichomes, and with glands, midvein indumentum cobwebby to hirsute; adaxial indumentum cobwebby to hirsute with septate trichomes. Foliaceous bracts subtending capitula 5–8 mm long, margin cobwebby. Capitula 25–35 mm wide, terminal, in panicles. Outer phyllaries broad-ovate, brown or straw-coloured, basal margin hispid, abaxial surface smooth, apex apiculate. Medial phyllaries ovate to narrow ovate, abaxially yellow, apex cuspidate. Stylar appendages narrowly triangular. Cypsela oblong, ~ 2.3 mm long and 0.75 mm wide, cross-section circular; pericarp grey–brown, idioblasts present. Pappus deciduous, ~ 6–7 mm long.

Distribution

Endemic to the northern end (‘Top End’) of the Northern Territory in the Darwin Coastal and Arnhem Coast bioregions ( Fig. 21 ).

Phenology

Recorded flowering August–October, with cypselae being recorded in October.

Habitat

Populations in the Darwin Coastal Bioregion commonly occur in eucalypt and Pandanus woodlands on sandy coastal plains with rare occurrences further inland on sandstone plateaux in the Mount Tolmer and Bundy Station areas, and on sandy clay seasonal swamps on the Cox Peninsula. Occurs on clay soils on the margins of the Arafura Swamp and gravelly loams in eastern Arnhem Land.

Notes

The largest populations seen during the course of this study were in areas that were patchily burnt as part of traditional land management practices in the early dry season (June–July) near the communities of Wadeye (U. Crocombe, pers. comm., 2018) and Mirrnatja (S. Guyula, pers. comm., 2018). Two populations from sandy clay seasonal swamps on Cox Peninsula have some individuals appearing to have rhizomatous stems, possibly adventitious roots in response to partial burial, and some with taproots. Molecular data indicated no genotypic differences within or between any X. boreale populations included in this study, and for this reason, we are not recognising rhizomatous plants as a different taxon.

Conservation status

Occurs over a large area, with some populations in the thousands recorded in 2018. Changes to land management and absence of traditional early dry season burning may be affecting some populations that could not be located in 2018 (T. L. Collins and J. J. Bruhl, unpubl. data). Plants at Dundee Beach in the Darwin Coastal Bioregion were affected by habitat loss as a result of coastal development and grassland mowing. We recommend a status of ‘ Least Concern ’ ( IUCN 2019).

Selected specimens examined

NORTHERN TERRITORY: Darwin and Gulf : Dundee Beach , S of Dunheved Road , 2 Oct. 2018, T.L. Collins 1088 & J.J. Bruhl ( CANB!, DNA!, NE!); Dhupuwamirri Road , on road to Mirrnatja , 9 Oct. 2018, T.L. Collins 1091 & J.J. Bruhl ( CANB!, DNA!, NE!); Mirrnatja, ~ 2.2 km N of village, 10 Oct. 2018, T.L. Collins 1092 & J.J. Bruhl ( CANB!, DNA!, NE!); Central Arnhem Road , Yunupingu Cattle Farm , 10 Oct. 2018, T.L. Collins 1093 & J.J. Bruhl ( CANB!, DNA!, NE!); Wadeye , Old Mission Road , 5 Oct. 2018, T.L. Collins 1089 & J.J. Bruhl ( CANB!, DNA!, NE!); Wadeye , on unnamed coast track , 5 Oct. 2018, T.L. Collins 1090 & J.J. Bruhl ( CANB!, DNA!, NE!). WESTERN AUSTRALIA: West Kimberley : West Kimberley , 1901, F.M. House s.n. ( PERTH!) . Wyndham–East Kimberley: Head of King Edward River , 7 Sep. 1921, C.A. Gardner 1565 ( PERTH!) .

Figures

Fig. 21. Distribution of Xerochrysum boreale.