Sonchus novae-zelandiae

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Sonchus novae-zelandiae

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Description

Rosulate, perennial, scapigerous herb arising from a stout, deeply descending, often multicipital tap root. All parts when broken leaking copious amounts of white latex exudate. Leaves and petiole 20–150 mm long, flattened, and more or less held appressed to the surrounding substrate; lamina crisply membranous, glabrous, lyrate, bright green, yellow green, or glaucous, sinuately shallowly to deeply, closely or distantly lobulate, or pinnatifid; lobules rounded, apical, often mottled with darker brown pigmentation or glaucous; terminal lobes 30–50 x 20–30 mm, lateral lobes diminishing in size from 10 to 1 mm, confluent, merging into the broadly winged petiole. Scapes 150 mm or more long, slender,initially sparsely and finely tomentose, becoming glabrous, except near capitulum; bracteate, bracts 1–5, linear, tomentose mainly with eglandular hairs, glandular hairs either absent or sparse. Capitula 15–30 x 10–40 mm, receptacle shallowly concave, alveolate. Involucrum 4-seriate, imbricating, membranous with scarious margins; outer involucral bracts 3–5 mm long, narrow-ovate, undersides densely tomentose with dark spreading glandular hairs; inner bracts narrowly ovate-oblong up to 15 mm long, dark brown-green, undersides intially clad in white tomentum and glandular hairs becoming glabrous, margins scarious with rather fine teeth. Florets 30–36, ligulate; limb pale lemon-yellow, about equal in length to the slender claw, apex deeply 5-fid. Style arms long, densely covered in minute processes, finely coiled. Anthers conspicuous. Fertile achenes few, 2–3 mm long, dark brown, slightly compressed, broad at first, apices bluntly obtuse to rounded, narrowed slightly to base, crowned with minute asperities glabrous, primary ribs longitudinal, 4–5, prominent; secondary ribs 4–5, less obvious, otherwise strongly transversely wrinkled towards base. Sterile achenes numerous, narrowly subcylindric, pale and finely ribbed. Pappus hairs up to 7 mm long, copious, white, slender and soft, fused at base otherwise barbellate in upper half.

from: New Zealand Plant Conservation Network (www.nzpcn.org.nz), under Kirkianella novae-zelandiae, at http://www.nzpcn.org.nz/c/flora/factsheets/NZPCN_Species_274.pdf, accessed April 2013.

Chromosome numbers

x = 9; in Sonchus novae-zenlandiae decaploid (2n = 90) and dodecaploid (2n = 126) cytotypes have been found (Beuzenberg & Hair 1984).A,B

Distribution

Australasia: New Zealand SouthnativeC,D (New Zealand SouthnativeC,D,E)

Threat status

Sonchus novae-zelandiae is endemic to and classified as "Vulnerable" in New Zealand. It is present in the South Island, growing in tussock grassland, river flats and slopes of colluvium, and possibly was formerly present also in the North Island but is now extinct there. Populations known from the Three Kings (Manawa-tawhi) islands) NW of the North Island, as well as from the Brother islands and Arapawa island in the Marlborough Sounds N of the South Island possible represent a separate taxonF

Bibliography

A. Beuzenberg E. J. & Hair J. B., Contributions to a chromosome atlas of the New Zealand flora — 27 Compositae in New Zealand J. Bot. 22: 353-356. 1984
B. Watanabe K., Index to chromosome numbers in Asteraceae.
C. Cheeseman T. F., Manual of the New Zealand Flora, ed. 2. 1925
D. Hooker J. D., Handbook of the New Zealand Flora: A systematic description of the native plants of New Zealand and the Chatham, Kermadec's, Lord Auckland's Campbell's and Macquarrie's Ilands. 1867
E. Wilton A. D. & al., Checklist of the New Zealand flora, seed plants. 2017
F. Lange, P. de & al., Threatened plants of New Zealand. 2010: 384-385 (as Kirkianella novae-zelandiae (Hook. f.) Allan)