Vernonieae (Asteraceae) of southern Africa: A generic disposition of the species and a study of their pollen
Author
Robinson, Harold
Author
Skvarla, John J.
Author
Funk, Vicki A.
text
PhytoKeys
2016
60
49
126
http://dx.doi.org/10.3897/phytokeys.60.6734
journal article
http://dx.doi.org/10.3897/phytokeys.60.6734
1314-2003-60-49
FFC26762742EFFBDFFAD0867FFB3FFBB
576336
Bothriocline Oliv. ex Benth.
Figures 1C
; 2B
; 4
A-C
Bothriocline
Hooker's
Icon. Pl. 12: 30, t. 1133. 1873. - Type:
Bothriocline schimperi
Oliv. & Hiern ex Benth.
Volkensia
O. Hoffm., Bot. Jahrb. Syst. 20: 219. 1894; Engl. & Prantl,
Natuerl
. Pflanzenfam. iv. 5: 387. 1893. - Type:
Volkensia argentea
O. Hoffm.
Resources.
Many species are keyed in
Jeffrey's
(1988)
treatment of
Vernonieae
in East Africa and in
Wild and Pope (1977)
,
Wild (1978a
,
1978b
).
Descriptions.
Perennial herbs (up to 1 m) to subshrubs, branching sparse, stems erect with a solid pith and long-armed T-shaped hairs with short 2-celled stalks. Leaves
alternate
, opposite or whorled, sessile to short petiolate, blade narrow to ovate or elliptical, pinnately veined, often paler or tomentose to sericeous below. Inflorescence laxly to densely corymbiform or thyrsiform cymes; heads pedunculate. Involucres campanulate, bracts ca. 50-60, gradate in 3-4 series, cuspidate at apex, with distinct pale or reddish lateral margins, nearly glabrous to pilosulous outside; receptacle convex, epaleaceous, with glabrous reticulum. Florets 3-100 or more in a head; corollas purplish, funnelform, basal tube slender with small stipitate glands, throat shorter than 1 mm, lobes, linear-lanceolate, with glandular dots and often with stiff subapical hairs; anther thecae blunt at base with few sterile cells; apical appendages ovate-oblong, with thin cell walls; style base with minimal annuliform node; sweeping hairs acicular, mostly restricted to branches. Achenes prismatic, short and broad with 3
-6(-
9) ribs, setuliferous with sparse short setulae scarcely split at tips, often densely covered with idioblasts and with scattered subquadrate raphids. Pappus of few or no short easily deciduous bristles narrowed at base, without obvious shorter ourter series or outer pappus a rim or collar. Chromosome number n = 9, 10, 18-20 (
Jones 1979
,
1982
). Pollen grains ca. 47
μm
in diam, lophate to rarely sublophate, finely echinate, pores in triplet of connected colpar lacunae, perforated tectum usually restricted to muri (Fig.
4
A-C
).
Figure 4.
Scanning electron micrographs of acetolyzed pollen of echinolophate
Bothriocline
and
Cyanthillium
and sublophate-lophate
Distephanus
.
A-C
Bothriocline schimperi
Oliv. & Hiern ex Benth.
A
Equatorial view, note incipient colpus of 3 connected lacunae centered on pore
B
Near polar view
C
Fractured grain
D-F
Cyanthillium cinereum
(L.) H. Rob.
D
Equatorial view
E
Lateral view with apertures on sides
F
Lateral view
G-I
Distephanus angustifolia
(DC.)
H
Rob. & B. Kahn.
G
Polar view
H
Equatorial view
I
Lateral view. (A-C,
F. Meyer 8159
; D-F,
Evans 344
; G-I,
Sidley 2211
).
Notable secondary metabolites include 5-alkylcoumarins and sesquiterpene glaucolides/hirsutanolides [
Bohlmann and Jakupovic 1990
, as
Bothriocline laxa
N.E. Br.,
Bothriocline longipes
(Oliv. & Hiern) N.E. Br.], and
Volkesia ripensis
Hutch. and 5-alkylcoumarins (
Bohlmann and Jakupovic 1990
, as
Erlangea fusca
S. Moore,
Erlangea rogersii
S. Moore).