Lapsanastrum

Primary tabs

Description

Herbs, annual or short-lived perennial, rosulate. Leaves pinnatipartite or pinnatisect. Capitula usually nodding, in fruit with 6–20 florets. Involucre narrowly cylindric at anthesis, broader in fruit, less than 7 mm, glabrous. Outer phyllaries much shorter than inner ones; inner phyllaries linear-lanceolate to lanceolate, of equal length, becoming broader in fruit. Receptacle naked. Florets yellow. Achene narrowly ellipsoid, subcompressed, with 5 main ribs and each accompanied by 1(or 2) secondary ribs, apex truncate but with 0 or (1 or)2–4 main ribs apically prolonged into 0.2–2.2 mm slender hooked appendages. Pappus absent.

from: Shih C. & Kilian N. in Wu Z. Y. & al. (ed.), Flora of China 20–21: 263. 2011, Beijing & St Louis.

Distribution

Asia-Temperate: China North-Central (Shaanxinative); China South-Central (Yunnannative); China Southeast (Anhuinative, Fujiannative, Guangdongnative, Guangxinative, Hunannative, Jiangsunative, Jiangxinative, Zhejiangnative); Japan (Hokkaidonative, Honshunative, Kyushunative, Shikokunative); Korea (South Koreanative); Taiwan (Taiwannative) Northern America: Oregon (Oregonintroduced)

Systematics

A cladistic analysis of morphological, fruit anatomical and chromosomal characters by Pak & Bremer (1995) revealed that the E Asian species of Lapsana share little more than the pappusless achenes with the remainder of this genus and are probably related rather to Youngia. Therefore Pak & Bremer (1995) transferred the four E Asian species to a new genus Lapsanastrum.

As has been noted by Pak & Bremer (1995), even habitually the species of Lapsanastrum are quite distinct, having a basal leaf rosette and weak or very reduced, almost leafless stems, while Lapsana s.str. has no basal leaf rosette and a well developed leafy stem. Moreover, the phyllaries in fruit are stellately spreading in Lapsanastrum but erect, indurate and keeled in Lapsana s.str. The achenes of Lapsanastrum have 5 main ribs, which are accompanied by 1(or 2) secondary ribs, whereas in Lapsana s.str. the achenes have c. 20 ±equal ribs. A peculiarity of the achenes in Lapsanastrum is that 0 or (1 or)2-4 of the main ribs are apically prolonged into 0.2-2.2 mm slender hooked appendages, most pronouncedly so in L. uncinatum (Stebbins 1938: 155, t. 27).

The close relationship to Youngia and distance to Lapsana assumed by Pak & Bremer (1995) have been fully confirmed in a recent molecular phylogenetic analysis by Deng & al. (2014): a member of that genus included in their analysis is even deeply nested within Youngia, indicating this lineage to have been evolved within Youngia.

References


Deng T., Zhang J.-W., Zhu X.-X., Zhang D.-G., Nie Z.-L. & Sun H. 2014: Youngia zhengyiana (Asteraceae, Crepidinae), a new species from south China, with notes on the systematics of Youngia inferred from morphology and nrITS phylogeny. – Phytotaxa 170: 259–268. // ➪ //

Pak J.-H. & Bremer K. 1995: Phylogeny and reclassification of the genus Lapsana (Asteraceae: Lactuceae). – Taxon 44: 13–21.

Stebbins G. L. 1938: An anomalous new species of Lapsana from China. – Madroño 4: 154–157.

Common names

Chinese (China): 稻槎菜属 dao cha cai shuA

Chromosome numbers

Diploids and tetraploid (L. apogonoides only), x = 8.B

Bibliography

A. Wu & al., Flora of China 20-21. 2011
B. Watanabe K., Index to chromosome numbers in Asteraceae.