Hybridization beyond the F₁ generation between the New Zealand endemic everlastings Anaphalioides bellidioides and Ewartia sinclairii (Asteraceae, Gnaphalieae)

Abstract

The Raoulia alliance is remarkable for the occurrence of rare wild hybrids between five of its six genera. In this study, the potential for hybridization beyond the F₁ generation between Anaphalioides bellidioides and Ewartia sinclairii was investigated. Three putative hybrids were raised from open-pollinated seeds collected from a site where wild A. bellidioides, E. sinclairii and their intergeneric hybrids occur. Multivariate analysis of morphological data strongly indicated that two of the seed-raised hybrids were backcrosses to A. bellidioides; the paternal parent of the third plant, raised from a seed collected from a wild hybrid, was equivocal. Artificial crosses and evaluation of seed germinability demonstrated that wild A. bellidioides × E. sinclairii are partially fertile and capable of giving rise to viable backcrosses and advanced-generation hybrids. Possible reasons for the apparent rarity of wild hybrids between A. bellidioides and E. sinclairii are discussed briefly.

Appendix

Morphological characters accessed and coding of character states for calculation of dissimilarities. 1, growth form: 0 = mat-forming to sprawling; 1 = subshrubby to erect; 2, rooting pattern: 0 = taprooted; 1 = adventitious roots produced along entire stem; 3, nonflowering shoot orientation: 0 = prostrate or decumbent; 1 = erect; 4, leaf length (mm); 5, leaf lamina width (mm); 6, leaf length: leaf lamina width ratio; 7, shape of lamina base: 0 = narrows abruptly; 1 = tapering; 8, stem enclosure by the leaf petiole extensions: 0 = ≤ 50% of stem enclosed; 1 = > 50 % of the stem enclosed; 9, mucro length (mm); 10, mucro orientation: 0 = recurved and pointing towards leaf axil (lamina/mucro angle < 90°); 0.5 = usually upturned (angle 90–180°); 1 = plane with leaf axis (angle ± 180°); 11, leaf indumentum density on adaxial lamina surface: 0 = dense; 1 = moderate; 2 = sparse to glabrous; 12, type B glandular trichomes on margins and adaxial surface of leaf: 0 = absent; 1 = present; 13, density of type B glandular trichomes on adaxial lamina surface and leaf margins: 0 = common; 0.5 = sparse or rare; 1 = absent; 14, terminal cell shape of type A glandular trichomes: 0 = oval; 0.5 = oblong-oval; 1 = oblong; 15, terminal cell length of type A glandular trichomes: 0 = 12–18 μm; 0.33 = 14–23 μm; 0.67 = 19–27 μm; 1 = 28–35 μm; 16, number of basal cells in clothing trichomes: 0 = always one cell; 1 = one or two cells; 17, base of terminal cell of clothing trichomes: 0 = swollen; 1 = not swollen; 18, lateral nerves raised on abaxial leaf surface: 0 = absent; 1 = present; 19, cuticle thickness: 0 = thicker on adaxial lamina surface; 1 = equal thickness on both lamina surfaces; 20, epidermis thickness: 0 = thicker on adaxial lamina surface; 1 = equal thickness on both lamina surfaces; 21, stomata level: 0 = level with epidermis; 0.5 = guard cells raised; 1 = guard cells and adjacent cells raised; 22, palisade chlorenchyma in midrib: 0 = absent; 1 = present; 23, abaxial collenchyma in midrib and lateral ribs: 0 = absent; 1 = present; 24, spongy mesophyll differentiation: 0 = well differentiated; 1 = slightly differentiated; 25, number of capitula per inflorescence; 26, capitulum length (mm); 27, capitulum width at midpoint (mm); 28, number of female florets per capitulum; 29, number of hermaphrodite florets per capitulu; 30, total number of florets per capitulum; 31, female floret: total floret ratio; 32, receptacle height (mm); 33, receptacle diameter (mm); 34, receptacle type: 0 = alveolate, foveolate or fimbrillate; 1 = scrobiculate; 35, inner involucral bract length (mm); 36, inner involucral bract, lamina length (mm); 37, shape of lamina tip of inner involucral bracts: 0 = acute to obtuse; 0.5 = obtuse to rounded; 1 = rounded; 38, reddish pigmentation in lamina/stereome gap of outer involucral bract: 0 = absent; 1 = present; 39, hyaline margins on stereome of inner involucral bract: 0 = absent; 1 = present; 40, corolla tube length in female florets (mm); 41, corolla tube length in hermaphrodite florets (mm); 42, upper corolla tube crimson at anthesis: 0 = absent; 1 = present; 43, corolla lobe colour at anthesis: 0 = green; 0.5 = greenish-white; 1 = white; 44, corolla lobes develop crimson pigmentation with age: 0 = absent; 1 = present; 45, corolla lobes recurved: 0 = erect only; 1 = at least some lobes partly patent or recurved; 46, crimson pigmentation in anthers: 0 = dark crimson; 0.5 = pale reddish; 1 = absent; 47, pollen colour: 0 = yellow; 0.5 = pale yellow; 1 = white; 48, style arm colour: 0 = white; 1 = pale green to greenish-white; 49, pappus hair length in female florets (mm); 50, female floret pappus hairs, number of apical cells: 0 = one or two; 1 = one to five; 51, female floret pappus hairs distinctly dimorphic: 0 = absent; 1 = present; 52, female floret pappus hairs, apical cells distinctly protruding: 0 = absent; 1 = present; 53, pappus hair length in hermaphrodite florets (mm); 54, hermaphrodite floret pappus hairs, number of apical cells: 0 = one or two; 0.5 = two to five; 55, type of wall thickening in pappus hair apical cells: 0 = reticulate or irregular; 1 = uniformly thickened; 56, density of basal cilia on pappus hairs: 0 = sparse; 1 = moderate to dense; 57, length of basal cilia on pappus hairs: 0 = up to 12 μm long; 0.5 = up to 25 μm long; 1 = maximum > 25 μm long; 58, angle of basal cilia on pappus hairs: 0 = ascending only; 1 = ascending, spreading or recurved; 59, ovary epidermal cell shape: 0 = rounded; 1 = smooth; 60, twin hairs on ovary of female florets; 0 = absent; 1 = present; 61, twin hairs on ovary of hermaphrodite florets: 0 = absent; 1 = present; 62, multicellular biseriate trichomes on ovary of female florets: 0 = absent; 1 = present.