Erica tetralix

Fagúndez, Jaime, 2012, Study of some European wild hybrids of Erica L. (Ericaceae), with descriptions of a new nothospecies: Erica nelsonii Fagúndez and a new nothosubspecies: Erica veitchii nothosubsp. asturica Fagúndez, Candollea 67 (1), pp. 51-57 : 55

4. Cross-pollination of Erica tetralix

and E. ciliaris

During the study of seed morphology of E. tetralix and related species ( FAGÚNDEZ & IZCO, 2009) one of the samples collected from an E. tetralix population clearly differed from the rest of the population with respect to the shape of the seeds and secondary sculpture. The seed morphology and details of the secondary ornamentation of this sample and a regular population of E. tetralix and E. ciliaris are shown in Fig. 2 . The seeds of E. tetralix are ovoid or ellipsoid, of ca. 0.4 mm, with a reticulate primary ornamentation and a smooth to vermiculate secondary sculpture of outer periclinal walls ( FAGÚNDEZ & IZCO, 2009). The seeds of E. ciliaris are similar in size, but with an oblong-ellipsoid shape, a very faintly reticulate pattern and an indented secondary ornamentation ( FAGÚNDEZ & IZCO, 2009). In this intermediate population, seeds are largely ellipsoid or ovoid, with a slightly reticulate pattern and an indented secondary ornamentation.

The parent plants were studied and the population was visited at the same locality in flowering time (Cercedo, July 2007, see specimens studied). This population is part of a humid heathland with Ulex L. where Erica ciliaris is abundant and E. tetralix occurs whenever soils are moist. The plants are E. tetralix with no intermediate characters. Thus, we conclude that these seeds are product of the pollination of E. tetralix plants with pollen from E. ciliaris .

Erica × watsonii ( E. ciliaris × E. tetralix ) is the most common of the European hybrids, described by BENTHAM (1839: 665) from plants found by H. Watson and well known in the British Isles ( HOOKER & ARNOTT, 1850: 255) and France EYRAUT, 1900; ROUY, 1908: 109). There are also references from the Iberian Peninsula ( PEREIRA- COUTINHO, 1939: 550; BAYER, 1993: 506) although we have not found any material or precise localities. In the British populations of E. ciliaris , where E. × watsonii is common, a very low percentage of seedlings have intermediate values for E. ciliaris and E. tetralix and may produce hybrid plants ( ROSE, 2007). In Spain no intermediates are commonly found although both species coexist in many localities (pers. obs.).

The indented surface in the secondary sculpture of the E. ciliaris seeds is uncommon for the European species of the genus. We have only recorded this feature in E. ciliaris and some populations of E. sicula Guss. ( FAGÚNDEZ & IZCO, 2011). The outer periclinal walls of the testa cells are collapsed to the inner walls that present pits, allowing the cell surface to display this indented pattern.

Specimens examined. – (sub. E. tetralix ). SPAIN. Pontevedra: Cercedo, Quireza , 42º34’48’’N 8º27’54’’W, 690 m, 28.IX.2006, 2.VIII.2007, Fagúndez 3266 ( SANT) . A Coruña: Carnota, O Pindo , 11.XI.1999, Fagúndez s.n. ( SANT-BG [119]) . Ciudad Real: Cabañeros, 2.X.2000, Fagúndez s.n. ( SANT-BG [211]) .

(sub. E. ciliaris ). SPAIN. Cádiz: Los Alcornocales , 25.IX. 2002, Fagúndez & Reyes s.n. ( SANT-BG [266]).

PORTUGAL: Matas de Faia , 11.IX.2001, s.coll. ( SANT-BG [273]).

Figures

Fig. 2. – Seeds of different species of Erica L. A: Erica tetralix L.; B: E. tetralix (detail of surface cells); C: E. tetralix × E. ciliaris; D: E. tetralix × E. ciliaris (detail of surface cells); E: E. ciliaris L.; F: E. ciliaris (detail of surface cells). [A: Fagúndez s.n., SANT-BG [119]; B: Fagúndez s.n., SANT-BG [211]; C-D: Fagúndez 3266, SANT; E: Fagúndez & Reyes s.n., SANT-BG [266]; F: Fagúndez & Reyes s.n., SANT-BG [273]]