Grimmia Hedw

Key to Grimmia species from South Africa and Lesotho As plants are often collected without sporophytes, and when present the sporophytes are often in poor condition, we have utilised only gametophytic characters. (Plants should be examined in the wet state). 1. Cross section of costa at insertion with 7 or more guide cells (see Fig. 8 G, H), in lamina with 2 guide cells sunken into narrow channel, their adaxial walls strongly thickened, at insertion with a small median band of substereids, interrupted by 3 groups or 1 large central group of hydroids that vanish in the apical part.............................. 6. G. laevigata 1a. Costa cross section at insertion with fewer than 7 guide cells............................................................................... 2 2. Costa cross section at insertion with 6 guide cells (see Fig. 9 F); in lower lamina costa unevenly rounded and somewhat angulate as seen in surface view, indistinct in apical part of leaf; basal cells with transverse walls markedly thinner than longitudinal...... 7. G. longirostris 2a. Costa at insertion with 4 guide cells or with 4 guide cells of which the outer two are contiguous with the basal cells.............................................................................. 3 3. Costa at insertion with 4 guide cells, outer guide cells non-contiguous with the laminal cells......................... 4 3a. Costa at insertion with 4 guide cells, the two outer ones contiguous with the laminal cells (see Fig. 3F, G; 6G, H)....................................................................... 12 4. Basal paracostal cells (excluding marginal cells) nodulose....................................................................... 5 4a. Basal paracostal cells (including marginal cells) smooth..................................................................................... 8 5. Transverse section of leaf base not concave, leaf base with a marginal border (see Fig. 5 F) of narrowly elongaterectangular, hyaline, thin walled cells in 3-4 rows, gradually transitioning to short-rectangular to quadrate cells but with outermost row ascending to above broadest part of leaf; margin recurved on one side from insertion to mid-leaf (see Fig. 5 C, D); lamina unistratose (see Fig. 5 H), rarely with bistratose patches..... 3. G. elongata 5a. Transverse section of leaf base concave, plants otherwise... 6 6. Transverse section of leaf above broadest part broadly keeled (see Fig. 7 I), unistratose at insertion and leaf base, partially bistratose in laminal part, bistratose in apex; margin with several rows of bistratose cells; costa in transverse section (see Fig. 7 I), with or without hydroids, cells in transitional part of leaf with walls smooth or sinuose (see Fig. 7 H).................................. 5. G. kidderi 6a. Transverse section of leaf above broadest part not broadly keeled; plants lacking the above combination of characters............................................................................... 7 7. Transverse section of costa at insertion with dorsal cell walls slightly bulging (see Fig. 13 J, K), below mid-leaf with 2 narrowly elliptical median guide cells arranged obliquely to leaf axis; marginal cells partly bi-tristratose in 1-3 rows above the leaf base; laminal cells in transitional zone elongate-rectangular (see Fig. 13 G, I), walls sinuose................................................... 11. G. pygmaea 7a. Transverse section of costa at insertion with dorsal cell walls bulging (see Fig. 11 H), the guide cells rounded, arranged horizontally; margin unistratose or at most bistratose in 1 cell row on one side in apex; lamina cells in transitional zone short-rectangular or isodiametric with walls smooth or slightly sinuose (see Fig. 11 G)............................................................................ 9. G. orbicularis 8. Cells in leaf base elongate-rectangular......................... 9 8a. Cells in leaf base short-rectangular............................ 11 9. Basal cells of upper stem leaves elongate-rectangular (see Fig. 14 D), with thickened transverse walls throughout; lower stem leaves with inner elongate rectangular and evenly thickened walls (see Fig. 14 E), but with 2-3 marginal rows short-rectangular to quadrate cells and with thickened transverse walls; margin (transverse section) (see Fig. 14 C) plane or occasionally recurved on one side from insertion to transitional zone (see Fig. 14 F)................................................ 12. G. sessitana 9a. Cells of leaf base elongate-rectangular, hyaline with cell walls evenly thin, margins plane................................. 10 10. Costa in transverse section markedly stout in the lamina (see Fig. 15 H), indistinct at apex, without hydroids but with abundant stereids; leaf forming a v-shape in crosssection in upper leaf................................ 13. G. tortuosa 10a. Costa in transverse section not markedly stout in laminal part, distinct at apex; transverse section with hydroids, stereids absent but substereids usually present; leaf section otherwise in upper leaf............... 2. G. donniana 11. Leaves abruptly lanceolate from ovate base (see Fig. 10 B), thus with distinct shoulders, keeled (transverse section) from mid-leaf to apex (see Fig. 10 H, I); in transverse section margin gradually incurved from base to apex (see Fig. 10 D, I), lamina bistratose (see Fig. 10 H, I), costa prominent above leaf base....................... 8. G. montana 11a. Leaves broad-lanceolate or lanceolate from a short, ovate leaf base, keeled from leaf base to apex (transverse section) (see Fig. 12 H, I), thus lacking distinct shoulders, in transverse section margin recurved on one side to above midleaf (see Fig. 12 C), rarely on both sides and then with one side recurved only at middle of leaf; lamina unistratose from insertion to apex (see Fig. 12 H), usually with marginal 1-2 cell rows that are bi- tristratose, occasionally only on one side and rarely unistratose (Fig. 12 I), costa prominent throughout..................................... 10. G. pulvinata 12. Costa in dorsal view strikingly small and thin from insertion to broadest part of leaf (Fig. 3B), becoming stout and prominent towards the apex; transverse sections of costa in the upper stout portion with a group of hydroids (see Fig. 3F, G); leaf bases auriculate, decurrent (see Fig. 3D)................................................ 1. G. consobrina 12a. Costa in dorsal view weak at insertion and leaf base but enlarged throughout laminal part (Fig. 6 B); above the broadest part of leaf the 2 median guide cells become narrowly elliptical and obliquely oriented to leaf axis (see Fig. 6 G, H); hydroids sometimes present in leaf base (see Fig. 6 H); leaf bases neither auriculate nor decurrent........................................................ 4. G. fuscolutea
Published as part of Eva Maier, Michelle J. Price & Terry A. Hedderson, 2017, A revision of Grimmia (Grimmiaceae) from South Africa and Lesotho, pp. 199-230 in Candollea 72 (1) on pages 203-204, DOI: 10.15553/c2017v721a12, http://zenodo.org/record/888344