Linzia Sch. Bip. ex Walp., 1843

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 : 78

Linzia Sch. Bip. ex Walp., 1843 Figures 13 B ; 15 A–B ; 16 A–E

Linzia Sch. Bip. ex Walp., Rep. 2: 948. 1843. - Type: Linzia vernonioides Sch. Bip. ex Walp.

Vernonia sect. Azurae S.B. Jones, Rhodora 83: 74. 1981. - Type: Linzia glabra Steetz in Peters.

Descriptions.

Perennial herbs; stems with simple multiseptate hairs. Leaves alternate, subsessile to short-petiolate. Inflorescence corymbiform cymes or single heads with short to long peduncles. Involucre funnelform to campanulate; bracts 50-150 in 5-6 series, often pectinate-denticulate with spicules along lateral margins, outer tips often elongate, green and recurved; receptacle epaleaceous. Florets ca. 20-50 in a head; cortollas bluish, tube very long, funnelform near throat; throat very short, lobes apically stiffly pilosulous; anther base rounded; apical appendage glabrous, triangular with thickened ornamentation in center; style base with small annuliform node. Achenes strongly 10-costate, usually with rows of idioblasts or specialized cells along sides of costae, surface setuliferous, setulae slender with pairs of cells not or scarcely separated at tip, raphids subquadrate to short-oblong; pappus of many somewhat persistent long bristles, with outer series short. Chromosome number n = 10 ( Jones 1979, 1982).

Pollen tricolporate, psilolophate, with spur muri intruding into short colpi above and below pore, single polar lacunae often present, not echinate, with or without micropunctations resticted to muri. Muri showing baculae with broadened base, branching distally into many bacula-like branches (Fig. 16 E ), a form that seems almost transitional to a rhizomate condition.

Most notable secondary metabolites, sesquiterpene germacranolides, elemanolides ( Bohlman and Jakupoic 1990, as Vernonia glabra Vatke & Vernonia melleri Oliv. & Hiern).

Figures

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 15. Photographs of Linzia and Namibithamnus: A-B Linzia glabra Steetz in Peters, note that the flowers bloom in two groups with the outer ones blooming first (light colored in 15 B) followed by the innermost ones (dark purple in 15 B) C-D Namibithamnus obionifolius (O. Hoffm.) H. Rob. See Appendix C for citation details.

Figure 16. Scanning electron micrographs of Linzia and Namibithamnus pollen. A, B, E Linzia rosenii. (R. E. Fries) H. Rob., Skvarla & V. A. Funk. A Polar view B Equatorial view C Equatorial view. Note differences of lophae surrounding pores in B and C, D Linzia glabra Steetz in Peters. Lateral view. E Linzia rosenii. Fractured pollen wall. F-H Namibithamnus obionifolius (O. Hoffm.) H. Rob., Skvarla & V. A. Funk. F Equatorial view. This is the most common form of aperture G Equatorial view. Less common form of aperture with broken lophal arms apparent H Near polar view (A-C, E Jacobsen 3075 D West 7292 F-H Toelken & Hardy 770).