Youngia in Flora of China @ efloras.org

66. Youngia Cassini, Ann. Sci. Nat. (Paris). 23: 88. 1831.

黄鹌菜属 huang an cai shu

Pseudoyoungia D. Maity & Maiti.

Herbs, perennial or annual, acaulescent or caulescent, often ± rosulate, glabrous or somewhat to sparsely arachnoid hairy or pubescent. Synflorescence corymbiform or paniculiform-corymbiform, exceptionally secundly racemiform. Capitula with 5-25 florets. Involucre cylindric, cylindric-campanulate, campanulate, or broadly cylindric. Phyllaries abaxially glabrous or more rarely somewhat arachnoid hairy, very rarely glandular; outer phyllaries few to several, centripetally longer, at most 1/4(-1/2) as long as inner ones; inner phyllaries usually linear-lanceolate, equal in length, midvein subapically crested and corniculate or flat. Receptacle naked. Florets yellow. Achene ± fusiform, columnar, or ± cylindric, inconspicuously compressed or subcompressed, with 4 or 5 main ribs each accompanied by (1 or)2 or more slender secondary ribs, ribs usually finely spiculate especially apically, apex attenuate or rarely with a stout short beak. Pappus white, rarely gray or pale brownish, scabrid.

About 30 species: E Asia; 28 species (22 endemic) in China.

The circumscription of Youngia has recently been changed by Sennikov and I. D. Illarionova (Komarovia 5: 96. 2008) based, in particular, on carpological analyses. Three species groups have been segregated into three newly established separate genera: Crepidifolium, Sonchella, and Tibetoseris. Crepidifolium includes Babcock and Stebbins’s (Publ. Carnegie Inst. Washington 484: 25. 1937) single species of their (not validly published) "Y. sect. Crepidopsis," meanwhile divided into three separate species. Most recent molecular phylogenetic analyses of the Crepidinae by J. W. Zhang et al. (in prep.) on the one hand confirmed that Crepidifolium is not part of Youngia, but on the other hand revealed that it is actually nested within Crepidiastrum, see there. Sonchella unites Y. stenoma of Babcock and Stebbins’s (not validly published) "Y. sect. Stenophytum" and a second species formerly treated as Prenanthes angustifolia or Crepis pratensis. This genus has been confirmed in the molecular phylogenetic analyses by J. W. Zhang et al. (in prep.) as independent and is treated as such here. Tibetoseris included the five species of Babcock and Stebbins’s (not validly published) "Y. sect. Desiphyllum" and a few later additions from China. Tibetoseris was most recently recircumscribed by D. Maity and Maiti (Compositae Newslett. 48: 22-42. 2010) to include only T. depressa, while the other species, considered from morphology as unrelated, were segregated into the newly established genus Pseudoyoungia. While their assumption of Tibetoseris being diphyletic has been confirmed in the molecular phylogenetic analyses by J. W. Zhang et al. (in prep.), the exclusion of the species united in Pseudoyoungia from Youngia has not; they appear clearly nested in Youngia. Pseudoyoungia is here therefore sunk in the synonymy of Youngia. Finally, examination of the type material of Y. blinii, considered as an unusual and isolated species of Youngia since its inclusion by Babcock and Stebbins (Univ. Calif. Publ. Bot 18(11): 227-229. 1943, as Y. setigera), revealed that it is grossly misplaced in Youngia but conveniently fits into Dubyaea, where it is transferred in the present treatment. The genus is still in need of a revision at species level. Many species are known from few collections only and their justifications need to be confirmed by a thorough study of character variation on the basis of more material. The current treatment should be used with critical caution.

1 Plants ca. 5(-8) cm tall, very rarely taller (to 15 cm) and acaulescent or stem very short and branched within or slightly above leaf rosette with capitula few to several, clustered; involucre 8-12 mm with longest outer phyllary 1/3-1/2(-2/3) as long as inner ones (2)

+ Plants caulescent, usually very distinctly so, or if stem very short then capitula not clustered but all borne distinctly above leaf rosette and longest outer phyllary usually at most 1/4 as long as inner ones (if 1/3-1/2(-2/3) as long see Y. conjunctiva above); involucre 5-13 mm (6)

2 (1) Peduncle slender; involucre 1.2-1.6 cm; pappus 10-11 mm. 3 Y. simulatrix

+ Peduncle capillaceous; involucre 0.8-1.1 cm; pappus 5-7 mm (3)

3 (2) Phyllaries abaxially arachnoid hairy. 6 Y. sericea

+ Phyllaries abaxially glabrous (4)

4 (3) Involucre 10-11 mm; longest outer phyllary 1/3-2/3 as long as inner ones; inner phyllaries adaxially appressed pubescent. 7 Y. conjunctiva

+ Involucre 8-10 mm; longest outer phyllary 1/3-1/2 as long as inner ones; inner phyllaries adaxially glabrous (5)

5 (4) Longest outer phyllary to 1/3 as long as inner ones; midvein of inner phyllaries subapically plane. 4 Y. gracilipes

+ Longest outer phyllary to 1/2 as long as inner ones; midvein of inner phyllaries subapically crested or corniculate. 5 Y. cristata

6 (1) Pappus ash-gray, yellowish brown, or pale brown (7)

+ Pappus white (10)

7 (6) Pappus ash-gray; synflorescence corymbiform on a stem with well-developed distant leaves (8)

+ Pappus yellowish brown or pale brown; synflorescence corymbiform on a leafless stem, or else not corymbiform (9)

8 (7) Peduncle and involucre ± shortly glandular hairy (rarely glabrous); midvein of inner phyllaries subapically always plane; style branches yellow upon drying. 1 Y. cineripappa

+ Peduncle and involucre glabrous; midvein of some inner phyllaries subapically crested or corniculate; style branches brown or green upon drying. 2 Y. atripappa

9 (7) Synflorescence corymbiform; capitula erect, with ca. 5 florets; involucre 6-7 mm. 27 Y. szechuanica

+ Synflorescence secundly racemiform; capitula nodding, with 10-20 florets; involucre 10-13 mm. 28 Y. racemifera

10 (6) Involucre 4-7 mm; synflorescence (except in depauperate plants) moderately to richly branched, with some, many, or numerous capitula; inner phyllaries with midvein subapically strictly plane (11)

+ Involucre (6-)7-10(-13) mm; synflorescence poorly to moderately branched, with few, some, or more rarely with many capitula; inner phyllaries either all with midvein plane or some with midvein subapically crested or corniculate (16)

11 (10) Leaves undivided; basal leaves with petiole to 15 cm, as long as hastate-cordate blade. 22 Y. longipes

+ Leaves except early basal ones always pinnately lobed; basal leaves with basal petiole-like portion much shorter than remainder of leaf (12)

12 (11) Basal, lower, and middle stem leaves bipinnately lobed, lateral lobes as broad as terminal lobe. 21 Y. rosthornii

+ Leaves at most pinnately lobed, lateral lobes usually much narrower and smaller than terminal lobe (13)

13 (12) Plants annual to perennial; stem leaves always well developed, pinnatipartite to pinnatisect, lateral lobes of all leaves ovate or elliptic, terminal lobe long acuminate; involucre 6-7.5 mm; achene 2.5-3 mm. 20 Y. heterophylla

+ Plants strictly annual; stem leaves mostly soon reduced and undivided, or if well developed and pinnately lobed then lateral lobes triangular or rhomboidal, terminal lobe obtuse, acute, or shortly acuminate; involucre 4-5(-7) mm; achene 1.5-2.5 mm (14)

14 (13) Achene light brown, dark reddish, or purplish brown, apex strongly attenuate; pappus persistent. 24 Y. japonica

+ Achene clear red, apex contracted into a stout 0.2-0.4 mm beak; pappus ± deciduous (15)

15 (14) Involucre 4-6 mm; pappus 2.5-3 mm. 25 Y. erythrocarpa

+ Involucre 6-7 mm; pappus 3-4 mm. 26 Y. rubida

16 (10) Midvein of all inner phyllaries plane (17)

+ Midvein of at least some inner phyllaries subapically crested or corniculate (20)

17 (16) Inner phyllaries adaxially glabrous; later basal and stem leaves pinnatifid to pinnatipartite, rachis often pectinate between lateral lobes. 17 Y. wilsonii

+ Inner phyllaries adaxially appressed pubescent; later basal and stem leaves pinnatisect, rachis not pectinate between lateral lobes (18)

18 (17) Lobes of pinnate leaves basally often with a large tooth; achene 3-3.5 mm. 18 Y. henryi

+ Lobes of pinnate leaves entire; achene 2-3 mm (19)

19 (18) Plants delicate, 10-30 cm tall; involucre ca. 7 mm; achene 2-2.5 mm. 15 Y. hastiformis

+ Plants usually rather robust, to 60 cm tall; involucre 7-11 mm; achene 2.5-3 mm. 16 Y. prattii

20 (16) Rosette leaves contracted or attenuate into a very long (to 9 cm) inconspicuously winged petiole-like basal portion at least as long as or longer than remainder of leaf. 19 Y. terminalis

+ Rosette leaves without petiole-like portion, or if with one then distinctly shorter than remainder of leaf (21)

21 (20) Involucre 8-13 mm; inner phyllaries adaxially pubescent; pappus 5-9 mm (22)

+ Involucre 6-8 mm; inner phyllaries adaxially glabrous or appressed pubescent; pappus 2.5-5.5 mm (23)

22 (21) Plants to 100 cm tall; involucre (0.8-)0.9-1.3 cm; longest outer phyllaries 1.5-3 mm. 8 Y. paleacea

+ Plants at most 30 cm tall; involucre 0.8-1 cm; longest outer phyllaries ca. 1.5 mm. 9 Y. pilifera

23 (21) Stem very slender or capillaceous, almost leafless or leafless with 1-5 capitula (24)

+ Stem usually more robust, usually with few leaves and more than 5 capitula (26)

24 (23) Involucre ca. (7-)8 mm; pappus 5-5.5 mm. 14 Y. kangdingensis

+ Involucre 6-7 mm; pappus 2-5 mm (25)

25 (24) Plants delicate, 3-10 cm tall; rosette leaves 1-7 × 0.3-1 cm; stem capillaceous; pappus 4-5 mm. 13 Y. yilingii

+ Plants more robust, 10-15 cm tall; rosette leaves 5-10 × 1-2 cm; stem slender; pappus ca. 2.5 mm. 23 Y. bifurcata

26 (23) Achene 2-2.5 mm; inner phyllaries adaxially pubescent (27)

+ Achene 3-4 mm; inner phyllaries adaxially glabrous or with only few appressed hairs (28)

27 (26) Leaves pubescent; longest outer phyllary to 1 mm; inner phyllaries adaxially densely appressed hairy. 12 Y. mairei

+ Leaves glabrous; longest outer phyllary 1-2 mm; inner phyllaries adaxially sparsely appressed hairy. 15 Y. hastiformis

28 (26) Stems especially at bifurcations, peduncles, and abaxial face of leaves brown arachnoid hairy; synflorescence with to 25 capitula. 10 Y. fusca

+ Stems, peduncles, and leaves mostly rather sparsely pale or white arachnoid hairy; synflorescence with less than 10 capitula. 11 Y. lanata

List of lower taxa