Corresponding author: Harold Robinson (
Academic editor: Alexander Sennikov
A new genus,
Since
The present review includes a full description of the plant, including SEM studies of pollen, and a formal description of the new genus.
Pollen from dried buds was obtained from herbarium sheets at the U.S. National Herbarium in Washington, D.C. Detailed light microscope analyses under a Wild light microscope using oil and immersion optics were made of pollen in the dry condition as well as after immersion in Hoyer’s solution (
Erect or decumbent perennial herbs from creeping rhizome or perennial root crown, all becoming erect, rosettiform, with erect pedunculate scapiform inflorescence; hirsute or pilose with long white hairs, hairs of stems, leaves and peduncles with cells uniseriate and with few short basal cells and long, acicular, rather stiff apical cell. Leaves alternate in loose basal rosette, mostly 2–4 cm long, petiole narrow, blade obovate, to 9 cm long and 1.5 cm wide, apically obtuse, cuneate into petiole at base, margins entire, slightly paler abaxially, pilose on margins and both surfaces, more densely pilose abaxially, few glandular dots adaxially, numerous dots abaxially. Scape mostly 5–11 cm long, densely and stiffly hirsute, sometimes with small bract near middle, bearing 1 terminal head. Heads broadly campanulate, up to 2 cm high, 1.5–1.8 cm broad. Involucre with ca. 15–20 persistent, mostly subequal ovate-lanceolate bracts in ca. 2 series, up to ca. 1.5 cm long, apices acute, without acumination, densely pilose outside with long simple hairs, with 3 longitudinal veins, margins narrowly scarious, sometimes reddish. Receptacle epaleaceous; florets ca. 40 in a head; corollas lavender, ca. 12 mm long, narrowly funnelform distally from slender basal tube, tube ca. 7 mm long, with stalked narrowly capitate glands outside, throat ca. 0.7 mm long, lobes linear, ca. 4.3 mm long, with glandular dots outside and numerous stiff uniseriate hairs distally; anther thecae ca. 3 mm long, with tapering bases, with short clavate tails, apical appendage oblong, glabrous, with tenuous cell walls; style base with narrow annular node; with acicular sweeping hairs restricted almost completely to branches; achenes weakly 5-costate, densely sericeous on and between ribs with long setulae, setulae slightly split at tips, glandular dots present near base, without evident idioblasts, raphids linear; carpopodium narrowly annuliform, with small quadrate cells; pappus of ca. 40 persistent barbellate bristles ca. 8 mm long, mostly of even width, tapering at extreme tips, with outer series of short narrowly lanceolate squamae. Chromosome number not known. Chemistry not known.
Pollen grains of
Herbarium specimen of
The genus is named for Colonel Paul von Lettow-Vorbeck, 1870–1964 (
The genus contains the following single species.
The species occurs primarily in the area of southwestern Tanzania north of lake Nyassa, and also in eastern Zambia, Ndola, Oct 1906,
Tanzania, Nyassa Hochland, Station Kyimbila, Rmubya Braubuligebirge, 1300–1500 m Seehöhe, 25 Nov 1907,
Evidently in savannah areas.
We wish to thank the former technician Brian Kahn for preparation of the pollen samples of