Myosotis

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Myosotis

Description

Perennial, biennial or annual herbs with alternate, lanceolate, oblanceolate or oblong leaves. Basal leaves stalked, stem leaves usually sessile or nearly sessile. Inflorescence scorpioid or terminated by a single flower, usually without bracts. Stamens with distinct filaments and anthers, that often have a rounded apical, more or less hood-shaped, hyaline appendix. Ovary 4-lobed, stigma either distinct, cushion-shaped, or indistinct, club-shaped.

Distribution

Patagonia: present temperate North America: present temperate and subarctic regions of the Old World: present
More than 100 species, most common in temperate and subarctic regions of the Old World, but also in the tropics at higher altitudes, section Exarrhena with its centre in New Zealand. A few species are also found in temperate North America, one species in Patagonia.

Taxonomy

As said above, Myosotis holds a very isolated position within the Boraginaceae and is best taken as the only member of the monotypic tribe Myosotideae Rchb. Closest affinities seem to be with Trigonocaryum formerly included in Myosotis as sect. Phyllocephalum Boiss., and probably also with Trigonotis.
Strophiostoma DC. was kept as a separate section for the presence of a distinct caruncula, which is a difference in quantity, not in quality, however, as there are small similar structures found also in other groups. At present, only two sections are discerned by authors such as Grau & Schwab (1982). I follow their descriptions here.

Section Myosotis: Stigma with small, well differentiated papillae, usually bilobed. Pollen grains small. Scales in corolla throat with long papillae: M. scorpioides L.

Section Exarrhena DC.: Stigma with large, clavate papillae, usually simple. Pollen grains large. Scales in corolla throat short: M. australis R.Br.

Uses

Myosotis spp. are frequently grown as ornamentals.

Notes

There are two distinct types of pollen size. Large-sized pollen is characteristic for species of the southern hemisphere together with the M. discolor group in the northern. It seems best suited to characterize section Exarrhena in a natural way. The genus is unique within the whole family by the spiral arrangement of the corolla lobes in bud. Another unusual feature is the sterile apical appendix of the anthers that consists of several layers of hyaline cells beyond the end of the vascular bundles. It is covered by the epidermis continuous with the rest of the anther and maybe either semicircular and dome-like or nearly ovoid and longer than wide. Its shape seems to offer a reliable distinctive character for various groups within the genus (Grau & Schwab 1982). Over-all shape as well as length and distribution of papillae of scales and stigma are likewise criteria of importance for systematics and lead to similar groups. Polyploidy is frequent on the basic numbers x = 9, 10, 11, 12. See .

Citation

Grau & Leins - in Ber. Deutsch. Bot. Ges. 1968: 107
Stroh - in Beih. Bot. Centralbl. 1941: 317
Grau & Schwab - in Mitt. Bot. Staatssamml. Munchen. 1982: 9
L., Gen. PL, ed. 5. 1754: 165