Corresponding author: Sukhonthip Bunwong (
Academic editor: Vicki Funk
Thailand. Prov. Udon Thani, rare on rocky areas in Phu Phrabat Historical Park. alt. 300 m,
Annual. Inflorescences axillary or terminal, pedunculate. Phyllaries imbricate in 5–6 series, arachnoid-glandular, apices purple. Differs from
Annual herbs, 50–100 cm tall.
Capitulescences,
SEM micrographs,
Endemic to Thailand. Only found in Phu Phrabat Historical Park, Udon Thani province.
Rocky areas of sandstone hills, scattering in dipterocarp forest, flowering from November and December.
1 | Phyllaries broadly ovate without margin spines | 2 |
– | Phyllaries broadly ovate with margin spines | 3 |
2 | Achenes 4–5-ribbed |
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– | Achenes 10-ribbed |
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3 | Achenes 5 (6–9)-ribbed |
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– | Achenes 10-ribbed | 4 |
4 | Phyllaries eglandular, margin spines to 10 mm long |
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– | Phyllaries glandular, margin spines to 5 mm long | 5 |
5 | Phyllaries acuminate; achenes 2.5–3 mm long |
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– | Phyllaries aristate or apiculate; achenes 1.5–2 mm long | 6 |
6 | Leaves with T-shaped hairs; phyllaries spinose ≤ 1 mm long |
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– | Leaves without T-shaped hairs; phyllaries spinose ≥ 1 mm long |
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The authors thank Maejo University Phrae Campus for financial support and acknowledge the curators and staff of the following herbaria for access to their facilities: AAU, BK, BKF, BM, CMU, E, K, KKU, L, P, QBG, and US. We also thank the editor and reviewers for their critical comments.