Ainsliaea DC. is an Asiatic genus of Mutisieae Cass. Forty-nine species and 19 varieties are recognized. Twenty-six species are endemic to China, four to Japan, four to Indo-China, two to the, Himalayas, and one to Taiwan. The genus is characterized by its stems unbranched, with leaves basally rosulate or congested at the median part of the stem (only one species has stems branched, with alternate leaves), capitula few-flowered, florets deeply 5-cleft with unilateral lobes, and plumose pappus. Three new combinations are made: Ainsliaea bonatii Beauverd var. multibracteata (Mattf.) S. E. Freire, A. glabra Hemsl. var. sutchuenensis (Franch.) S. E. Freire, and A. henryi Diels var. subalpina (Hand.-Mazz.) S. E. Freire. One variety, A. latifolia (D. Don) Sch. Bip. var. taiwanensis S. E. Freire is described for the first time. The following taxa are newly synonymized: A. macroclinidioides, Hayata var. secundiflora (Hayata) Kitam. and A. secundiflora Hayata with A. apiculata Sch. Bip. var. acerifolia Masam.; A. aptera DC. f. paniculata Kuntze with A. aptera DC.; A. pteropoda DC. var. platyphylla Franch. with A. bonatii Beauverd; A. mattfeldiana Hand.-Mazz. with A. bonatii var. multibracteata; A. cleistogama C. C. Chang with A. cavaleriei H. Lev.; A. asarifolia Hayata, A. cordifolia Franch. & Sav. var. integrifolia Maxim., A. fragrans Champ. ex Benth. var. integrifolia (Maxim.) Kitam., A. integrifolia (Maxim.) Makino, A. ningpoensis Matsuda, and A. rubrifolia Franch. with A. fragrans Clamp. ex Benth.; A. lancifolia Franch. with A. glabra Hemsl.; A. tenuicaulis Mattf., A. glabra var. tenuicaulis (Mattf.) C. C. Chang, and A. plantaginifolia Mattf. with A. glabra Hemsl. var. sutchuenensis (Franch.) S. E. Freire; A. angustifolia Hook. f. & Thoms. ex C. B. Clarke with A. glumacea (Fr.) Sch. Bip.; A. gracilis Franch, var. robusta Diels with A. grossedentata Franch.; A. morrisonicola Hayata, A. reflexa Merr. var. morrisonicola (Hayata) Yamam.. A. henryi Diels var. ovatifolia C. C. Chang, A. reflexa Merr. var. nimboram Hand.-Mazz., and A. latifolia (D. Don) Sch. Bip. var nimborum (Hand.-Mazz.) Kitam. with A. henryi var. subalpina; A. petelotii Merr. with A. hypolenca Diels ex H. Limpr.; A. hui Diels ex Mattf. with A. kawakamii Hayata; A. heterantha Hand.-Mazz. with A. latifolia (D. Don) Sch. Bip.; and A. tonkinensis Merr., A. longipetiolata Merr., and A. reflexa Merr var. lobbiana Beauverd with A. reflexa Merr. lotypes tire newly designated for Ainsliaea DC., Ainsliaea sect. Aggregatae Beauverd, A. apiculata Sch. Bip., A. aptera DC., A. cordifolia Franch. & Sav., A. crassifolia C. C. Chang, A. dentata Koidz, A. dissecta branch. & Sav., A. elegans Hemsl., A. elegans var. strigosa Mattf., A. fulvipes Jeffrey & W. W. Sm., A. glabra Hemsl.. A. h:hypoleuca Diels ex H. Limp r., A. macroclinidioides,s Hayata, A. multibracteata Mattf.. A. ovalifolia Vaniot, A. pertyoides Franch.. A. pertyoides var. albotomentosa Beauverd:, A. peryoaide.s vat. intermedia Beauverd:rd, A. plantaginifolia Mattf., A. pteropoda DC.. A. pteropoda vat. macrocephala Maul., A. pteropoda var. pint.)phylla Franch.. A. pteropoda var. silhetensis DC., A. scabrida Dunn, A. tenuicaulis Mattf.,A. yadismae Koidz., and Hieracium glumaceum Fr. Neotypes are designated for A. apiculata Sell. Bill. var. acerifolia Masam., A. apiculata Sell. Bill. var. ovati(folia Masam., A. cordifolia Franch. & Sav. var. integrifolia Maxim., and A. linearis Makino. Epitypes ante designated hit A. cordifolia Franch. 8 Sav., A. dissecta Franch. & Sav., and A. pteropoda DC. Phylogenetic analysis of Ainsliaca based oi 30 morphological characters produced three most parsimonious trees that support the monophyly of the genus. Pertya Sch. Bip., Myripnois Bunge, and Macroclinidium Maxim. are the genera closest to Ainsliaea, and it is hypothesized that Pert pi is ancestral to the fatter three. Ainsliaea is distinguished from Pertya. Macroclinidium, and Myripnois by its usually plumose pappus bristles (vs. scabrid pappus bristles in the other three genera). Pltylogenetic analysis also supports the existence of two subgenera, i.e., Ainsliaca sub g. Ainsliaea, with distinctly uniseriale pappus bristles, and the monospecific Ainsliaea subg. Diaspananthus (Miq.) Kitam. (A. uniflora. Sell. Bip.) from Japan, characterized by its pappus of biseriate bristles. Phylogenetic resolution within subgenus Ainsliaea is weakly supported. However, the best supported resolution divides subgenus Ainsliaea into three subclades: two agree with two of three; previously proposed sections, and the remaining basal third subchade is monospecific (A. lancangensis Y. Y. Qian). Two sections previously recognized, section Ainsliaea (= section Scaposae Beanverd including section Frondosae Beauverd) and section Aggregatae Beauverd, are tentatively proposed until more appropriate characters have been found. A key to the species of the genus is provided, as well as morphological descriptions, illustrations, and distribution maps.