Flora of the Canadian Arctic Archipelago
English: Saxifrage family.
Saxifragaceae, Saxifrage family.
Vegetative morphology. Plants 1–15(–35) cm high; perennial herbs; caespitose, or not caespitose; sometimes vegetatively proliferating by bulbils on stems or leaves, or sometimes vegetatively proliferating in inflorescences, or never vegetatively proliferating by bulbils on stems or leaves, in inflorescences, from gemmiphores and gemmae, or by fragmentation. Taproot present, or only fibrous roots present. Ground level or underground stems horizontal, or absent (usually), or vertical; stoloniferous (S. flagellaris), or rhizomatous (Chrysosplenium, S. rivularis); elongate, or compact. Horizontal stems at ground level, branching extensively to shape plant habit as mats, or cushions. Caudex present, or absent. Aerial stems erect, or decumbent (less commonly), or prostrate. Leaves heterophyllous (varying between the basal leaves and leaves on the flowering stems), or not heterophyllous; basal in a rosette, or mainly basal, or distributed along the stems; patent, or erect; alternate (usually), or opposite (S. oppositifolia); persistent, or dying annually and non-persistent, or marcescent. Petioles present, or absent; 0–20(–50) mm long; glabrous, or hairy; puberulent, or pubescent, or pilose, or villous. Petiole hairs shorter than the diameter of the petiole, or longer than the diameter of the petiole. Leaf blades simple. Leaf blade bases cordate, or truncate, or obtuse, or cuneate, or attenuate. Blades 2–70 mm long (mean 13 mm), 0.4–35 mm wide (mean 7 mm), linear or oblong or elliptic or circular or lanceolate or ovate or oblanceolate or obovate or spatulate or reniform or triangular, flat, veins palmate (Chrysosplenium, Saxifraga cernua, and S. rivularis) or appearing single-veined or with inconspicuous veins. Blade adaxial surface glabrous or hairy, hairs glandular (usually). Blade abaxial surface glabrous or glabrescent. Blades lobed or not lobed. Blade margins entire or glandular-dotted or serrulate or serrate or crenate or deeply divided, with 7–10 glands per cm, with non-glandular hairs or glabrous or with glandular hairs, with 3–7 teeth on each side of the blade, with teeth toward the apex; degree of incision 50–70%. Hydathodes present and conspicuous, or present but inconspicuous, or absent. Blade apices acute, or obtuse, or acuminate, or rounded.
Reproductive morphology. Plants monoecious (S. eschscholtzii), or bisexual. Flowering stems without leaves, or with leaves. Flowering stem glandular hairs present. Flowers solitary, or in inflorescences. Inflorescences with bulbils, or without bulbils; spicate, or racemose, or paniculate, or cymose, or head-like; terminal; 0–3(–10) cm long. Pedicels present, or absent. Flowers per inflorescence 1–15; small, or medium-sized; radially symmetrical (actinomorphic); unisexual, or bisexual. Sepals conventional; 4 (rarely), or 5 (usually); free; 0.5–3 mm long; (1–)2.5–7 mm wide; green (usually), or yellow, or purple, or red; herbaceous, or scarious. Calyx hairy, or glabrous. Calyx margins ciliate, or margins without cilia (usually). Petals conventional, or absent; free; shorter than the calyx, or same length as the calyx, or longer than the calyx (more commonly); 5; green, or white, or yellow, or red, or pink, or purple; with contrasting markings, or without contrasting markings; elliptic, or ovate, or obovate, or lanceolate, or oblanceolate, or spatulate; unlobed; 1–10(–15) mm long; (0.4–)1–4 mm wide. Stamens 4–10 (4–8 Chrysosplenium, 5 stamens plus 5 staminoidia, Parnassia, 10 stamens, or 5 stamens and 5 staminoidia, Saxifraga 10 stamens); stamen filaments glabrous; free of the corolla. Anthers purple, or purple becoming yellow, or yellow; short-cylindrical, or ovoid, or sub-globose; 0.2–1 mm long. Nectaries present. Receptacle 0.1–7 mm high. Ovary superior, or partly inferior, or inferior; carpels 2 (usually), or 4 (Parnassia); syncarpous, or partly fused. Ovaries glabrous. Styles present (very short), or absent. Placentation axile. Ovules per ovary 25–120. Fruit with calyx persisting; dry; a capsule; spherical, or ellipsoid, or ovoid; brown, or red, or purple, or green at maturity, or golden brown, or straw-coloured; (2.5–)3–10(–12) mm long; (1.5–)3–12 mm wide; hairy (rarely), or glabrous (usually); dehiscent; splitting to the base into separate segments. Seeds 25–50(–120); 0.4–1.5 mm long; black, or brown, or yellowish; surfaces smooth, hairy, verrucose, ridged, winged.
General notes. Warming (1909) documented five growth forms among Arctic Saxifragaceae.
1. Species with leaves in a rosette and a vertical rhizome. The primary root dies early, and numerous adventitious roots develop. New shoots develop in the axils of the upper leaves: Micranthes (S.) hieracifolia and M. (S.) nivalis. Parnassia would be included here.
2. Species with vertical rhizomes, foliage leaves in a loose rosette, bulbils or runners with scale leaves or reduced foliage leaves, and adventitious roots: Chrysosplenium, S. cernua, S. hirculus, and S. rivularis.
3. Species in which the main stem is vertical and bears a close rosette of leaves and many adventitious roots. The stem dies away completely after flowering. Lateral shoots arise from the leaf-axils in no fixed order, develop more or less horizontally along the ground for some distance, and terminate in a new rosette: S. paniculata and S. flagellaris.
4. Species with a many headed rhizome and a primary root that remains alive for a long time. Adventitious roots are few in number, and vegetative propagation is by lateral shoots becoming independent: S. cespitosa and S. tricuspidata.
5. Creeping herb species in which the shoots are prostrate and have their internodes more or less elongated, with a primary root that appears to be able to live several years: S. eschscholtzii, S. oppositifolia, and S. aizoides.
The following species have been noted as evergreen but not to the same extent: S. aizoides, S. cespitosa, S. hieracifolia, S. nivalis, S. oppositifolia, S. paniculata, and S. tricuspidata. Old dead leaves persist for a long time especially on those species that belong to dry habitats: S. cespitosa, S. hieracifolia, S. nivalis, and S. oppositifolia.
Flowers develop the year previous to that in which they open in S. cespitosa, S. hieracifolia, S. nivalis, S. oppositifolia, S. rivularis, and possibly all species. Staminate flowers occur rarely in S. oppositifolia, but pistillate flowers, which are smaller than the hermaphroditic ones, appear to be common in several species. Stamens are present, but smaller than usual and not fully developed.
Normal flowers have 10 anthers and two carpels, but other numbers have been observed, for example, 6 and 7-merous gynoecia in S. cernua. Trimerous gynoecia have been found in S. aizoides, S. cespitosa, and S. tricuspidata, and 4-, 5-, and 6-merous in S. oppositifolia. The flowers have nectar secreted at the base of the gynoecium, and in some instances, scent has been noted. Protandry, the maturation of the stamens before the stigmas, has been observed in Chrysosplenium, S. aizoides, S. paniculata, S. cespitosa, S. cernua, S. hieracifolia, S. hirculus, S. nivalis, S. rivularis, and S. tricuspidata. Protogyny, the ripening of the stigmas before the anthers, occurs in S. cernua, S. cespitosa, S. hieracifolia, and S. nivalis, but only slightly. However, S. oppositifolia is distinctly protogynous. Self-pollination is uncommon, but may occur when anthers touch stigmas. Fruit set and seed formation is common in many species. Seed ripens in most species but possibly not every year in every locality. Those that do not set seed at all, or do so rarely, are S. cernua and S. foliolosa. They vegetatively propagate primarily.
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..