Micromorphology of endemic Centaurea glaberrima subsp. divergens (Asteraceae)

Abstract

In this study, the micromorphology of the vegetative and reproductive structures of the endemic Centaurea glaberrima Tausch subsp. divergens (Vis.) Hayek (Asteraceae), using scanning electron microscope (SEM), is presented for the first time. Uniseriate whip-like non-glandular and biseriate glandular trichomes are found on the surface of all aboveground parts (stem, leaves, peduncles, involucral bract). On the adaxial leaf epidermis ribbed thickenings (striation pattern) of outer periclinal cell walls, slightly curved anticlinal cell walls and anomocytic stomata are noticed. Rugose abaxial surface with thorny protuberances of the involucral bract is documented. Corolla is glabrous with longitudinally parallel epidermal cells with distinct straight outline. Isopolar, radially symmetric and tricolporate microechinate pollen grains are seen. Short stylar hairs, without cuticular striations, are present along the outer sides of the style, while the inner sides (abaxial surface) constitute the papillate stigmatic surface. Microcharacters found in cypsela are as follows: slightly ribbed body; rotund base; lateral and concave insertion; short, unicellular curly acute trichomes; smooth epidermis; fine-sulcate ornamentation; rod shaped epidermal cells with short, obtuse end walls and straight anticlinal walls; poorly developed minutely dentate pericarp rim; and dimorphic pappus with bristles of different length and morphology, with pinnules restricted to the margins of the bristles. The results obtained contribute to knowledge about the micromorphology of the studied endemic species and provide features for its better identification. The taxonomic significance of the analyzed characters is discussed. Some well defined microcharacters of the studied species might have taxonomic value

Seed Morphological and Anatomical Structures as Taxonomy Tool for Turkish Hyacinthella Schur (Asparagaceae) Taxa

“…4). The characters in statistical analysis were utilized seed colour: black (1), brown (2); seed shape: triangularis (3), circularis (4), ellipticus (5), ovatus (6), ellipticus-late (7); seed size: length (8), width (9), length/width (10); seed ornamentation type: rugose (11), reticulate-pusticulate (12), verrucate (13), tuberculate (14), ruminate (15), reticulate-foveate (16), alveolate (17); anticlinal cell wall: unclear (18), at (19), raised (20), sunken (21); periclinal cell wall: unclear (22), concave (23), convex (24); epidermal cell structure: unclear (25), polygonal (26), alveolar (27); anatomical structure of epidermis: crushed (28), at (29), polygonal (30); presence of subepidermis layer (31); anatomical structure of subepidermis: at (32), polygonal (33); testa thickness (34); cotyledon size: length (35), width (36); embryo shapes: elongated (37), ellipticus (38), ovatus (39), circularis (40); embryo size: length (41), width (42). The dissimilarity matrix of the examined species was formed with MVSP (Kovach 2007) (Table 4).…”

Centaurea lovricii, a new species of C. sect. Centaurea (Asteraceae) from Croatia

“…Another morphologically similar species is C. divergens (Fig. 6), which is often treated as a subspecies or variety of C. glaberrima (Malý 1928;Hayek 1931;Lovrić 1967Lovrić -1968Dostál 1976;Gavrilović and Janaćković 2022), but its treatment as a distinct species, as proposed by Visiani (1847) and Hayek (1901), seems to be more appropriate (see Table 1). It differs from C. lovricii in having a hispid stem, rigid and dull green basal leaves with linear-filiform leaflets (0.5-2 mm wide), a 6-10 mm long involucre, phyllaries that are up to 8 mm long, with up to 2 mm long fimbriae, outermost sterile florets with a 5.5-6 mm long corolla tube, and up to 1.1 mm long pappus bristles.…”