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On Circumscription of the Genus Cicerbita Wall., and Two New Genera of Compositae from Sino-Himalayan Region

Shih Chu   

  • Received:1900-01-01 Revised:1900-01-01 Online:1991-09-10 Published:1991-09-10
  • Contact: Shih Chu

Abstract:

Dealt with in the present paper is a comparatively complex group of plants with
an outermost ring of short pappus at the apex of achenes in the tribe Lactuceae of
Compositae from the Sino-Himalayan Region. The group includes plants with rostrate
achenes and those with achenes non-rostrate, neither broadened, nor thickened or both
broadened and thickened margins as well as those with both heads polyanthous and plants
with heads reduced to only 3 florets. The previous taxonomical treatments of the complex
group may be considered unnatural. These non-Lactuca plants were treated either as mem-
bers of the genus Lactuca, or as those of the genus Cicerbita.
     In order to provide a clear and natural classification for these extremely complex group
of plants from the Sino-Himalayan Region, it is first necessary to clear up the concept of the
genus Cicerbita. Cicerbita, as a genus, was separated from Lactuca and established by
Wallarth as early as in 1822 based on Lactuca alpina etc., but its circumscription was unclear
at the beginning. In his concept, Cicerbita covers not only plants with rostrate achenes, but
also plants non-rostrate achenes. The concept of Cicerbita had not been clear until its
lectotype was chosen. That is to say, only those plants with combination of non-rostrate
achenes and an outermost ring of short pappus at the apex of achenes in the tribe Lactuceae
can be regarded as the members of the genus Cicerbita. Such a concept of Cicerbita deffers
not only from the one of B. Beauverd, who placed genera, such as Mycelis Cass., Mulgedium
Cass., Steptorhamphus Bunge and Cephalorrhynchus Boiss., into Cicerbita respectively as sec-
tion, but also from the one of G. L. Stebbins, who also used strict concept of Cicerbita.
     On the basis of the concept of Cicerbita mentioned above, through identification of
specimens with an outermost ring of short pappus of the tribe Lactuceae in the
Herbarium of Institude of Botany, Academia Sinica, recognized are four species from
China in the genus, i. e. Cicerbita oligolepis Chang, sp. nov., C. tianschanica (Rgl. et
Schmalh.) Beauverd, C. azurea (Ledeb.) Beauverd and C. sikkimensis (Hook. f.)
Shih.
     With the concept of Cicerbita thus defined the related group of plants from the
Sino-Himalayan Region can now be further treated. One of them, like the plants of
Cicerbita, has an outermost ring of short pappus at the apex of achenes also, but by its
Achenes with broadened and thickened margin, acute or acuminate, extending into a ros-
trum at its apex, the group differ not only from Cicerbita with erostrate achenes, but also
from Lactuca without an outermost ring of short pappus at apex of achenes.
Unfortunately, some species in the group of the Sino-Himalayan Region were placed in
the genus Lactuca by predicessors. In fact, This is a new genus, Chaetoseris Shih.
     The genus Chaetoseris Shih seems to be more similar to Cephalorrhynchus Boiss with
achenens neither broadened, nor thickened along its margins than to Cicerbita Wallr.
     All of 18 species of Chaetoseris Shih are distributed in the Sino-Himalayan
Region. They are Chaetoseris grandiflora (Franch.)  Shih, Ch. dolichophylla Shih,
Ch. leiolepis Shih, Ch. taliensis Shih, Ch. macrantha (C. B. Clarke) Shih, Ch. ciliata
Shih, Ch. hastata (Wall. ex DC.) Shih, Ch. cyanea (D. Don) Shih, Ch. macrocephala
Shih, Ch. lyriformis Shih, Ch. hispida Shih, Ch. roborowskii (Maxim.)  Shih, Ch.
likiangensis (Franch.) Shih, Ch. sichuanensis Shih, Ch.  pectiniformis Shih, Ch. lutea
(Hand. -Mazz.) Shih, Ch. rhombiformis Shih and Ch. yunnanensis Shih
     Another group of Compositae which is represented by Lactuca graciliflora Wall. ex
DC. etc. and distributed in the Sino-Himalayan Region, and has an outermost ring of
short pappus at the apex of achenes, evidently should not be regarded as the members of
Lactuca. With a combination of usually fine cylindrical, calyculate involucres, 3
phyllaries arranged in 1 row, and heads with 3 florets and achenes broadened and thick-
ened along its margins the group should be regarded as a new genus, Stenoseris
Shih. This new genus seems to be similar to Mycelis Cass., with achenes neither broad-
ened, nor thickened along its margins and yellow florets rather than to Chaetoseris
Shih. Stenoseris Shih, distributed in the Sino-Himalayan Region, has five species. They
are St. graciliflora (Wall. ex DC.) Shih, St. taliensis (Franch.) Shih, St. tenuis Shih,
St. leptantha Shih and St. triflora Chang.
    On the basis of the concept of Cicerbita, the present author provides in this paper a
revision for plants in the Sino-Himalayan Region previously placed in Lactuca. In this
sense, the present paper can be regarded as a continuation of “REVISION OF
LACTUCA  L. AND  TWO  NEW  GENERA  OF  TRIBE  LACTUCEAE
(COMPOSITAE)  ON  THE  MAINLAND  OF  ASIA”   published  in  Acta
Phytotaxonomica Sinica before.

Key words: Compositae, Lactuceae, Cicerbita, Chaetoseris, Stenoseris, Cephalorrhynchus

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