Flora of the Canadian Arctic Archipelago
English: Knotted pearlwort,
French: Sagine nouseuse.
Caryophyllaceae, Pink family.
Published in Rhodora 80: 28. 1978.
Type: Canada, Quebec, Gaspé County, 19.08.1905, Collins and Fernald 75. Holotype: MSC.
Synonymy. Sagina nodosa f. bulbillosa Polunin, Bull. Natl. Mus. Canada 94 (Biol. Ser. 24): 205. 1940.
Vegetative morphology. Plants 3–10 cm high; perennial herbs; caespitose; sometimes vegetatively proliferating by bulbils on stems or leaves (bulb-like fascicles of axillary reduced leaves). Taproot present. Ground level or underground stems horizontal; stoloniferous; elongate; 0.5–0.8 mm wide. Caudex absent. Aerial stems decumbent. Aerial stem trichomes spreading, or erect. Leaves distributed along the stems, or basal in a rosette; opposite; marcescent. Petioles absent. Leaf blade bases cuneate. Leaves not grass-like. Blades 5–12(–25) mm long, 0.3–0.7 mm wide, spreading, linear, flat or folded, with inconspicuous veins. Blade adaxial surface dull, glabrous. Blade abaxial surface glabrous. Blade margins glabrous; apices acute.
Reproductive morphology. Plants bisexual and agamospermic. Flowering stems two or more per plant; with leaves. Flowering stems hairy. Flowering stems pubescent. Flowering stem hairs simple; white or translucent (if applicable); glandular hairs present. Flowers solitary (usually), or in inflorescences. Inflorescences with flowers in a dichasium. Flowers per inflorescence 1–3; medium-sized. Sepals conventional; 5; free; (2.5–)3–3.5(–4.5) mm wide; green; herbaceous. Calyx glabrous (usually), or hairy (rarely). Calyx hairs glandular; white or translucent (if applicable). Petals conventional; free; longer than the calyx (about twice as long as the sepals); 5; white; obovate; unlobed; 4.5–6 mm long. Stamens present; 10; stamen filaments glabrous. Anthers yellow; ovoid; 0.8–1 mm long. Ovary superior; carpels 5; syncarpous. Ovaries ovate; glabrous. Styles present; 5; free; 2.5–3.5 mm long. Stigmas per ovary 1. Placentation free central. Ovules per ovary 15–25. Fruit with calyx persisting; dry; a capsule; ovoid; straw-coloured; 3–4.5 mm long; 1.5–2.5(–2.9) mm wide; surface appearing veinless; dehiscent; opening with teeth at the top of the capsule (splitting almost to the base); teeth 5. Seeds several; 0.5–1 mm long; brown; surfaces verrucose.
Chromosome information. 2n = 56.
2n = 56. Löve (1970a, Iceland); Löve and Löve (1982, central Canada).
Ecology and habitat. Substrates: river terraces; seepage slopes; rocks, gravel, moss; with low organic content, peat (restricted to coasts); acidic, or calcareous. Restricted to coasts, growing in moist crevices of rocks wet gravels and sands and in tufts of moss along rocky coasts.
North American distribution. From New England north and infrequently to Baffin Island (Crow 1978). Continental Northwest Territories, Nunavut Islands, continental Nunavut, northern Quebec, Labrador. Range in the Canadian Arctic Archipelago limited. Rare. Low Arctic. Arctic islands: Baffin, Southampton.
Northern hemisphere distribution. Amphi-Atlantic (broadly). Northern Iceland, Northern Fennoscandian, KaninPechora, Taimyr Severnaya Zemlya, AnabarOlenyok, Kharaulakh, Central Canada, Labrador Hudson Bay, West Greenland, East Greenland.
General notes. Crow (1978) stated that Sagina nodosa is the most clearly defined species of the genus and that its floral morphology most nearly represents that of the ancestral type. In this species, the petals (4.5–6 mm) are much longer than the sepals (3–4.5 mm long), and leaves of the upper main stem and lateral branches usually bear axillary fascicles of minute, succulent leaves, giving a "knotted" appearance.
Crow (1978) divided S. nodosa into two subspecies, (i) subsp. borealis with glabrous stems or with scattered glandular hairs at the nodes, pedicels, and calyx bases, and (ii) subsp. nodosa with glandular hairs on the stems, pedicels, calyx bases, and frequently also the leaf margins. In North America, subsp. borealis is widespread, whereas subsp. nodosa occurs only on part of the eastern coast (possibly introduced from Europe). Crow (1978) noted that subsp. nodosa is the more widespread subspecies in northern Europe, while subsp. borealis is found only in the previously glaciated regions of northern Europe.
Karlsson, in Jonsell (2001a), reported that plants in Norden (the area treated by Flora Nordica) vary not only in hairiness, but also in habit, length of shoots and leaves, flower size, and number of flowers and bulbils. Plants from glabrous populations (subsp. nodosa) are often prostrate, have shorter stems, shorter rosette leaves, and usually more flowers per shoot, and produce few or no bulbils. Karlsson, in Jonsell (2001a), tentatively accepted the subspecies proposed by Crow (1978), but mentioned that a large part of the Nordic material cannot be assigned to one or the other of these two forms.
Polunin (1940b) described a form from Baffin Island, S. nodosa f. bulbillosa, which occurs totally without flowers and produces bulbils in the axils of cauline leaves. The disarticulation of these tiny fascicles of leaves in the fall is the normal mechanism of vegetative dispersal, which occurs with greatest frequency at higher latitudes. It is not restricted to sterile plants (Crow 1978). Similarly, purely bulbiliferous plants, not worthy of rank, occur throughout the range of subsp. borealis, either as populations or within populations with some flowering.
Illustrations. • Close-up of plant. Flowering plants growing in dry, sun-baked dolomite gravel. The stolons are seen against the white marker. The petals are between 4.5 and 6 mm long. Manitoba, Churchill, Beech Bay, in the tidal estuary of the Churchill River, south of the Port, 58°44.30'N, 94°08.06'W. Aiken and Brysting 01–032. CAN. Scale bar in cm. • Close-up of stems and leaves. Leaves 5–12 mm long, linear and glabrous. Note bulbils, axillary fascicles of minute leaves in the upper axils. Manitoba, Churchill, Beech Bay, in the tidal estuary of the Churchill River, south of the Port, 58°44.30'N, 94°08.06'W. Aiken and Brysting 01–032. CAN. Scale bar in cm. • Close-up of flower. Flower with five unlobed petals. Note the 10 stamens and 5 styles. Manitoba, Churchill, Beech Bay, in the tidal estuary of the Churchill River, south of the Port, 58°44.30'N, 94°08.06'W. Aiken and Brysting 01–032. CAN. • Type specimen. Holotype of Sagina nodosa f. bulbillosa Polunin. Nunavut, Baffin Island, Kimmirut (Lake Harbour). 27 August, 1936. Polunin 2312. CAN 52919. • Arctic Island Distribution.
This publication is available on the internet (posted May 2011) and on CD-ROM (published in 2007). These versions are identical in content, except that the errata page for CD-ROM is accessible on the main index page of the web version.
Recommended citation for the web-based version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. NRC Research Press, National Research Council of Canada, Ottawa. http://nature.ca/aaflora/data, accessed on DATE.
Recommended citation for the CD-ROM version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. [CD-ROM] NRC Research Press, National Research Council of Canada, Ottawa..