Cortaderia selloana subsp. selloana

Testoni, Daniel & Linder, H. Peter, 2017, Synoptic taxonomy of Cortaderia Stapf (Danthonioideae, Poaceae), PhytoKeys 76, pp. 39-69 : 46-47

1a. Cortaderia selloana subsp. selloana Figs 1A , 2A-B

Common names.

pampas grass, cortadera, cola de zorro, carrizo de las pampas. The origins of the popular name "pampas grass" are somewhat obscure, and do not reflect the ecology of the species ( Stapf 1897).

Taxonomy.

Cortaderia selloana ssp. selloana can be diagnosed by the glumes about as tall as the basal lemma, and lemma without a distinct awn. The plants are generally larger than those of Cortaderia araucana and Cortaderia speciosa , and the panicles are larger (0.5 to 1 m long), more lax, and coloured white, pink or yellowish. The similar size of basal lemmas and glumes (6-15 mm) further separates it from Cortaderia araucana (glumes 9-17 mm long, ca. ½ length of basal lemmas), whereas the larger glumes separate it from Cortaderia speciosa (glumes 6-8 mm, ca. ¾ length of basal lemmas). The large size may also lead to confusion with Cortaderia nitida , but it is easily separated by the larger and laxer panicles, 3-veined, awnless lemmas that are glabrous on hermaphrodite plants; and female plants with tiny staminodes. For the distinction from ssp. jubata see below.

Cortaderia selloana ssp. selloana was originally described as dioecious, but Astegiano et al. (1995) showed that it is gynodioecious, and Testoni and Villamil (2014) recorded several populations with only pistillate individuals (so presumably apomictic) in central and northern Argentina. This subspecies presents the greatest morphological variability and geographical range in the genus. The morphological characterization is also complicated by interbreeding between natural populations and cultivated plants.

Figures

Figure 1. Lemmas of selected species of Cortaderia. A Cortaderia selloana, Juergens 40 (B) B Cortaderia araucana, Borchers s. n. (US) C Cortaderia speciosa, P. M. Peterson 12766 (US) D Cortaderia vaginata, L. B. Smith, P. R. Reitz & R. Klein 7761 (B) E Cortaderia egmontiana, P. M. Peterson, R. J. Soreng & N. Refulio-Rodriguez 17508 (US) F Cortaderia modesta, A. Chase 8288 (US) G Cortaderia hieronymi, A. Burkart et al. 30395 (P) - note that awn and setae are much longer than illustrated H Cortaderia nitida, S. Laegaard 52786 (K) I Cortaderia sericantha, E. Asplund 17175 (B) J Cortaderia bifida, D. N. Smith & J. Cabanillas 7167 (US) K Cortaderia hapalotricha, J. C. Solomon & R. Chevalier 16620 L Cortaderia columbiana, J. P. Schulz 318 (US). All at same magnification.

Figure 2. Leaf anatomy of Cortaderia, as evident from transverse sections. A-B Cortaderia selloana (Villamil 11738) C Cortaderia speciosa (Testoni 644) D Cortaderia vaginata (Zanin 1654). Comparison of bulliform cells in Egmontiana group: E Cortaderia egmontiana (Testoni 634) F Cortaderia modesta (Carauta 927) G Cortaderia vaginata (Zanin 1654). Structures referred to in the descriptions are labelled as follows: 1, multi-layered abaxial sub-epidermal collenchyma layer; 2, aerenchyma; 3, chlorenchyma; 4, primary vascular bundle; 5, midrib; 6, colourless cells; 7, empty cells; 8, bulliform cells.