Hilliardiella H. Rob., 1999

Robinson, Harold, Skvarla, John J. & Funk, Vicki A., 2016, Vernonieae (Asteraceae) of southern Africa: A generic disposition of the species and a study of their pollen, PhytoKeys 60, pp. 49-126 : 72-74

Hilliardiella H. Rob., 1999 Figures 11 A–D ; 12 A–D ; 13 A ; 14 A–H

Hilliardiella H. Rob. Proc. Biol. Soc. Wash. 112(1): 247. 1999. - Type: Vernonia pinifolia (Lam.) Less.

Webbia DC., Prodr. 5: 72. Oct 1836, nom. illeg., not Webbia Spach, Jun 1836.

Vernonia subsect. Hilliardianae S.B. Jones, Rhodora 83: 66. 1981. - Type: Vernonia oligocephala (DC.) Sch. Bip.

Descriptions.

Herbaceous perennials to 1 m tall; stems pilose, hairs unequally T-shaped. Leaves alternate; blades abaxially often densely canescent pilose. Inflorescence laxly to subdensely corymbiform-cymose. Heads short-pedunculate; involucres campanulate, bracts 25-40, in ca. 3-4 series, persistent; receptacle epaleaceous. Florets 12-20 in a head; corollas purple, outside with few to many slightly contorted T-shaped hairs; basal tube funneliform above, throat short, lobes linear; anther thecae not or shortly appendaged at base; apical appendages glabrous, with thin walls; style with basal node; style branches with acicular sweeping hairs. Achenes 4-5-costate, densely setuliferous, setulae scarcely divided at tips, idioblasts numerous, raphids elongate, carpopodia narrowly cylindrical; pappus bristles white, barbate, tenuous, subpersistent, outer series shortly lanceolate. Chromosome number of n = 9, 10, most reports n = 10 ( Turner and Lewis 1965; Jones 1982).

Pollen grains sublophate, with continuous perforated tectum between colpi, tricolporate to poles, echinate (Fig. 14 A–H ).

Notable secondary metabolites; acetones & sesquiterpene glaucolides/ hirsutanolides ( Bohlmann and Jakupovic (1990, as Vernonia sutherlandii Harv., guaianolides, bisabolene derivatives ( Bohlmann and Jakupovic 1990, as Vernonia hirsuta Sch. Bip. ex Walp. and Vernonia oligocephala (DC.) Sch. Bip. ex Walp.).

Figures

Figure 11. Photographs of Hilliardiella. A-B Hilliardiella aristata (DC.) H. Rob. C-D Hilliardiella flanaganii (E. Phillips) H. Rob. See Appendix C for citation details.

Figure 12. Photographs of Hilliardiella oligocephala (DC.) H. Rob.: A Habit B Close up of head C Characteristic leaf D heads in fruit. Note: discolorous leaves are characteristic of some but not all species of Hilliardiella. See Appendix C for citation details.

Figure 13. Illustrations Hilliardiella, Linzia, Parapolydora, and Vernonella: A Hilliardiella capensis (Houtt.) H. Rob., Skvarla & V. A. Funk B Linzia glabra Steetz in Peters, note: characteristic teeth on involucral bracts C Parapolydora gerrardii (Harv.) H. Rob D Vernonella africana Sond. See Appendix C for citation details.

Figure 14. Scanning electron micrographs of acetolyzed pollen from two collections of Hilliardiella capensis emphasizing spine variations. The surface seems to vary between sublophate and slightly echinolophate. A Polar view B Equatorial view C Lateral view D Polar view E Equatorial view F Subpolar view G Fragmented pollen surface H Grain fragment showing structural support of spine. (A-C Bayliss BS 3686 D-H Gentry & Barolas 18914).