Spoon-leaved moss (Bryoandersonia illecebra) COSEWIC assessment and status report: chapter 3

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Species information

Name and classification

Bryoandersonia illecebra was originally described by Hedwig as Hypnum illecebrum, based on a Pennsylvania specimen. North American specimens were recognized as distinct from similarly named European ones as early as 1805 (cited in Palisot-Beauvois in Koch 1949), and were historically distinguished by names such as H. illecebrum var. americanumBrid. and Cirriphyllum boscii(Schwägr.) Grout. (Koch 1949). The acceptance of Hedwig's Species Muscorum as the starting point of moss nomenclature invalidated the Linnaeus name. Bryoandersonia illecebrum (Hedw.) H. Rob was named in honour of Lewis E. Anderson, by one of his students (Robinson 1962). According to Crum and Anderson (1981), “illecebra” means “attractive, or alluring”.

The genus Bryoandersonia is monotypic, and belongs to the large and variable moss family Brachytheciaceae (division Bryophyta, subdivision Musci, order Hypnales).

Description

Bryoandersonia illecebrais large and easily identified in the field. Full descriptions of this species are found in Robinson (1962) and Crum and Anderson (1981). Selected illustrations from these sources are reproduced, with permission, in Figure 1. Photographs are provided in Figure 2.  Definitions for technical terms used in the description below (and elsewhere in this report) can be found in Crum and Anderson (1981) or in Magill (1990).

General

Bryoandersonia illecebra is a robust, shiny, pleurocarpous moss that grows in green-yellow-brown mats. It branches freely, with the branches ascending, julaceous (reminiscent of rat’s tails in older material (Crum and Anderson 1981]), and blunt-tipped ( Figures 1, figure 2 2).

Leaves

Leaves of the stems and branches are not differentiated, and measure 1.3 to 2.8 mm in length. They are imbricate (closely appressed and overlapping) when dry and spreading when moist. Leaves are concave (hence the common name “spoon-leaved moss”), smooth, broadly ovate from a non-decurrent, cordate base, and abruptly acuminate. Leaf tips are twisted when dry. Leaf margins are plane, erect and serrulate from apex to base. The single, slender costa (leaf midrib) ends about 4/5 of the way up the leaf (Figure 1).

Figure 1. Illustration of Bryoandersonia illecebra, reproduced (with permission from The Bryologist and Columbia University Press) from Robinson (1962) (A.-I.) and Crum and Anderson (1981) (J.).

1. Median leaf cells
2. Leaf
3. Cells of leaf base
4. Stem segment with leaves
5. Cells of upper leaf margin
6. Portion of stem cross-section
7. Capsule with operculum, dry
8. Capsules with opercula, moist
9. Capsules with opercula, moist
10. Portion of branch.

Figure 2. Bryoandersonia illecebra

1. B. illecebra near Paynes Mills in Elgin County, Ontario, displaying diagnostic '‘rat-tail'’ form.
2. B. illecebra in the Cedar Creek ANSI in Essex County, Ontario. The end of a fine-tipped ‘Sharpie’ marker is used to demonstrate the relatively robust size of this moss species.

Leaf cells

Leaf cells are linear, firm-walled and slightly wavy, becoming shorter and with constrictions (pitted) at the base. Alar cells (at the lower corners of the leaves) are subquadrate (square-ish), thick-walled, pitted, and opaque, occurring in small groups ( Figure 1).

Seta

The smooth, red seta (stalk supporting the spore-filled capsule) is 13 to 25 mm long.

Capsule

Capsules are smooth, strongly inclined, curved, asymmetric, and 2 to 3 mm long. The operculum (lid of the capsule) has a long beak, or narrow point ( Figure 1). The peristome teeth, which surround the opening of the capsule, are narrow and yellow-brown.

Sexuality

Bryoandersonia illecebra is dioicous, meaning that male organs (antheridia) and female orgrans (archegonia) occur on separate plants.

Bryoandersonia illecebra is readily distinguished from superficially similar taxa by its long-beaked operculum, bluntly-julaceous branches and deeply-concave leaves (Crum & Anderson 1981). Robinson (1962) points also to the stem cross section, in which all cells have rather thick walls (Figure 1), and to the auriculate leaf bases (Figure 1B). Cirriphyllum species may look similar to B. illecebra, but are less robust, julaceous, and stiff. Pseudoscleropodium purum (Hedw.) Fleisch. resembles B. illecebra even more, particularly with respect to its size and texture. However, P. purum (not known from Ontario) is considerably more pinnate-branched.