Alchemilla subcrenata

GROWTH FORM

Moderately mat-forming herb with very stout, horizontal rhizome densely covered with marcescent, blackish petioles and leaf sheaths. Rhizome branching at irregular intervals, resulting in open clones of shoots at ground level. Aerial shoots with 2—4 or more basal leaves. Stems ascending from the caudex just beneath the leaf rosettes, with patent or retrorse hairs. Stems leaves 2—4, smaller and more short-petiolate than the basal ones.

LEAF

Leaves alternate, with petioles up to 10—12 cm and with patent to retrorse hairs. Blades nearly orbicular in outline, up to 8 × 9 cm, slightly plicate, with palmate venation and ca. 9 triangular—rounded, dentate lobes, basal lobes of the leaf characteristically up-turned (‘swan wings’). Blade lower surface with spreading hairs (especially on veins), upper surface sparsely hairy, especially as narrow belts of hairs along the folds between the blade lobes. Each lobe with (13)15(17) subacute teeth, often irregular in size with the largest teeth on the middle part of the lobe margins.

INFLORESCENCE

Inflorescence an open, composite cyme with numerous loose clusters (cymes), each with 10—30 flowers on short pedicels. Main branches of the inflorescence with patent hairs, secondary branches and pedicels glabrous.

FLOWER

Flowers radially symmetric, epigynous (perianth attached above the gynoecium) with an urn-shaped, glabrous hypanthium, with 4 short epicalyx bractlets and sepals, no petals, yellowish green. Sepals short triangular, with a few apical hairs or glabrous. Stamens 4. Gynoecium of one carpel. Style basal, short, surrounded by a ring-formed discus.

FRUIT

Fruit a nut enclosed in the hypanthium.

REPRODUCTION

Asexual reproduction by seeds (agamospermy); local vegetative reproduction by fragmentation of rhizome. Seed production needs pollination for development of the endosperm that furnishes nutrients for embryo development (a phenomenon named pseudogamy). Whether any seed reproduction occurs in Svalbard is unknown, but improbable. Fruits have no special adaptation to dispersal, probably spread very locally by wind and animals.

COMPARISON

Alchemilla subcrenata differs from the assumedly native A.glomerulans (on Bjørnøya) in hairs on stems and petioles patent or slightly retrorse, in loose clusters of flowers, and in leaves with a rather dense pubescence and with hairs on the upper surface concentrated to the folds between the lobes. In A. glomerulans the hairs on stems and petioles are appressed, the cymes very dense (‘glomeruli’), and the leaves have a sparse but even pubescence.

HABITAT

Ruderal ground by cabins and within a settlement. Little is known of the site types in Svalbard.

DISTRIBUTION

Introduced. Alchemilla subcrenata had a stand of flowering plants near a cabin at Krillvatnet on Bjørnøya in 1957, but this stand was not refound during searches in 1964 or 1967 (see Engelskjøn & Schweitzer 1970). There are, however, one or more stands within the Russian settlement of Barentsburg on Spitsbergen (Nordenskiöld Land), observed repeatedly from 1988 to 2011. The plant is obviously introduced in Svalbard and may not reach reproductive stage there. It flowered on Bjørnøya but has not yet been observed flowering in Barentsburg. It sustains well by vegetative growth.

The global range is European and W Siberian.

COMMENTS

The genus Alchemilla is one of the larger agamosperous groups of Rosaceae with 400—500 reported species (or microspecies) in Europe (Kurtto et al. 2007). It is nearly confined to Europe and W Siberia (with some shrubby species or a related genus in the East African high mountains), but a few species transgress the Atlantic to Iceland and Greenland and 1—2 species to Jan Mayen and Bjørnøya. As all investigated European and North Atlantic species are agamospermous, only a single fruit is needed to start a new population. The source area of every Atlantic Alchemilla is Europe (there are no endemic species in Iceland, Greenland or the arctic islands). This vouches for a rather efficient dispersal across the sea. As no species of Alchemilla have fruits with any floating ability, this is an indirect support for the importance of bird dispersal.

LITERATURE

Engelskjøn, T. & Schweitzer, H.J. 1970. Studies on the flora of Bear Island (Bjørnøya). I. Vascular plants. – Astarte 3: 1–36.

Kurtto, A., Fröhner, S.E. & Lampinen, R. 2007. Atlas florae europaeae. Distribution of vascular plants in Europe. 14. Rosaceae (Alchemilla and Aphanes). – The Committee for Mapping the Flora of Europe and Societas Biologica Fennica Vanamo, Helsinki.