Chara wightii (A.Braun) Casanova, Austral. Syst. Bot.

Casanova, Michelle T. & Karol, Kenneth G., 2023, Charophytes of Australia’s Northern Territory - I. Tribe Chareae, Australian Systematic Botany 36 (1), pp. 38-79 : 72-74

Chara wightii (A.Braun) Casanova, Austral. Syst. Bot.

26: 293 (2013)

Chara flaccida var. wightii A.Braun, Hooker ’ s J. Bot. Kew Gard. Misc. 1: 296 (1849). Type: Madras (Chennai), India, between 1819 and 1849, R.Wight 133 (holo: BM!; iso: L!). Chara fibrosa subsp. flaccida Zaneveld , nom. inval.: J. S.Zaneveld, Blumea 4: 162 (1940) p.p. Chara fibrosa var. flaccida J.C.van Raam , nom. inval.

[ Chara fibrosa auct . non C.Agardh ex Bruzelius: R.D.Wood, Taxon 11: 13 (1962), p.p.]

[ Chara fibrosa f. fibrosa auct. non C.Agardh ex Bruzelius: R.D.Wood, Rev. Characeae 1: 289 (1965), p.p.]

Monoecious. Plants 100–250 mm high, often calcified, somewhat shrubby ( Fig. 21 a ). Axes up to 700 µm in diameter; internodes regularly 2× corticated axis, isostichous or tylacanthous (20–22 cells around) ( Fig. 21 d ). Spine cells small and conical on older axes, longer on young axes, occurring singly, 130–185 μm long and 20–40 μm wide. Stipulodes in a single whorl, the same number as the number as branchlets in each of the whorls ( Fig. 21 b ), 1–2 mm long. Branchlets 9–11 in a whorl, 5–14 mm long, segments 4–6, the basal cell shorter than the second cell in fertile whorls ( Fig. 21 b ). Bract cells 4–6 verticillate at the branchlet nodes, up to 0.4–2.5 mm long, bracteoles 2, similar to bract cells ( Fig. 21 c ). Gametangia conjoined singly or geminate at the lowest 2–4 branchlet nodes. Oosporangia up to 500 µm long and 375 µm wide, 10 or 11 stripes of helical cells, coronula up to 75 µm high, cells apiculate and spreading slightly. Oospores chestnut brown at maturity, 400–470 µm long, 250–310 µm wide ( Fig. 21 e ). Striae of 7–10 low ridges (in Australian material usually 7 or 8), fossa wall 64 μm across ( Fig. 21 f ), basal cell impression ~80 µm wide at the widest point ( Fig. 21 g ). Antheridia up to 500 µm in diameter, octoscutate. Chromosomes not known.

Distribution

Northern Australia, India and South-East Asia ( Pal 1932; Pal et al. 1962; Han and Li 1994; Langangen and Leghari 2001). Mostly freshwater.

Etymology

Named for the collector of the type material, Robert Wight (director of the Botanic Garden in Madras [now Chennai ] from 1819 to 1853) .

Notes

Chara wightii has a corticated axis and naked branchlets and it is often encrusted with calcium carbonate; it is characterised by brown oospores and occasional geminate gametangia, in contrast to C. benthamii and C. duriuscula , which have black oospores and singular gametangia. It can be distinguished from C. erythrogyna (which has sejoined gametangia) by its consistently conjoined gametangia and brown oospores. Australian material tends to be isostichous rather than tylacanthous, but it is included within C. wightii pending further investigation.

Specimens examined

NORTHERN TERRITORY: 20 km SW of Wombungi, Fitzmaurice River area, 15 May 1994, S. McCune 7 & P. Munns (DNA); lagoons on upper Elkedra River , 7 May 1977, T. S. Henshall 1745 (DNA); Port Darwin , 9 Apr. 1896, T. B. Blow A102 ( BM) . WESTERN AUSTRALIA: Caliwingina Spring, 1 Aug. 2011, M.Curran 1 ( PERTH); Arnhem Land, Wilton River , near Bulman, 9 Nov. 1987, G. J.Leach & C. R.Dunlop 1633 (DNA) .

Figures

Fig. 21. Chara wightii, (a–d) from specimen S.McCune 7 & P.Munns (DNA), (e–g) from the holotype material R.Wight 133 (BM) (a) Longitudinal view of the axis with cortication and spine-cells, scale bar: 1 mm. (b) Fertile whorl, scale bar: 5 mm. (c) Gametangia at branchlet node with bract cells and bracteoles, scale bar: 5 mm. (d) Transverse section of the corticated axis, scale bar: 1 mm. (e) Scanning electron micrograph (SEM) of oospore, scale bar: 100 µm. (f) SEM of detail of oospore wall, scale bar: 20 µm. (g) SEM of basal view of oospore showing impression of the basal cell, scale bar: 100 µm.