Poa bulbosa L., Sp. Pl. 70. 1753 subsp. bulbosa

Ortega-Olivencia, Ana & Devesa, Juan A., 2018, Updated checklist of Poa in the Iberian Peninsula and Balearic Islands, PhytoKeys 103, pp. 27-60: 27

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Poa bulbosa L., Sp. Pl. 70. 1753 subsp. bulbosa


15. Poa bulbosa L., Sp. Pl. 70. 1753 subsp. bulbosa 

Poa bulbosa subsp. eu-bulbosa  Hayek, Prodr. Fl. Penins. Balcan. 3: 259. 1932, nom. inval.

Ill. Ruiz (1991: 31, lam. III), Devesa (1987: 265).


"Habitat in Gallia" (lectotype designated by Meikle 1985, pg. 1742; restricted by Soreng 2000, pg. 255: Hasselquist, Herb. Linn. No. 87.57!).


January to July (December).


Pastures and grasslands in wet and nitrified soils, less frequently in ephemeral pastures and dry places; edaphically indifferent; 0−3100 m a.s.l.


Europe, SW, C and N Asia until W China, Africa and Macaronesia (Madeira and Canary Islands); introduced in the Americas, Australia and Pacific Islands. Entire Iberian Peninsula and Balearic Islands. And. Port.: Ag AAl BAl BA BB BL DL E Mi R TM. Spa.: A Al Ab Av B Ba Bu C Ca Cc (Cs) CR Co Cu Ge Gr Gu H Hu J L Le Lo Lu M Ma Mu Na Or O P PM[Mll (Me)] Po S Sa Sg Se So SS T Te To V Va Vi Z Za. For a representative list of studied materials, see Suppl. material 1.


According to Bolòs and Vigo (2001: 380), reports of Poa bulbosa subsp. concinna  (Gaudin) Hayek, Repert. Spec. Nov. Regni Veg. Beih. 30(3): 260. 1932 [ P. concinna  Gaudin, Agrost. Helv. 1: 196. 1811, basion., type: "Hab. in arenosis Valesiae inferioris, praecipue Seduni"; P. perconcinna  J.R. Edmonson, Bot. J. Linn. Soc. 76: 330. 1978, type: based on P. concinna  Gaudin] in E Spain are mistaken, as this taxon is actually only distributed from SE France to the Balkan Peninsula. That taxon differs from P. bulbosa  by their smaller sizes and narrower leaves, 0.8-2.2 mm ligules and never-proliferating spikelets with 6-10 flowers. In a few peninsular populations, plants with spikelets bearing 9-10 flowers have been detected, but they coincide with P. bulbosa  in all other characters.

Caryopses are formed in this species, but sexual reproduction is infrequent; more common propagation routes include the formation of bulbs at the base of the plant or bulbils at the inflorescence level. This latter phenomenon, pseudovivipary, is extraordinarily frequent in P. bulbosa  and involves the formation of bulbils for vegetative multiplication in the place of normal flowers ("proliferated spikelets"; Ofir and Kigel 2014). These bulbils may or may not coexist with normal flowers on the same spikelet or plant or in the same population. The balance between clonal and sexual reproduction is controlled mainly by day length and temperature; short days and low temperatures usually promote proliferating inflorescences, whereas long days and high temperatures induce normal and seminiferous ones. The proliferating spikelets usually carry (1-) 2-3 bulbils and have deformed floral parts: the glumes are usually narrower, the lemma is typically long (up to 20 mm), thin and either glabrous or only hairy on the central and marginal veins and the palea is missing or fully integrated into the bulbil, similar to the lodicules. Stamens are also missing or very reduced in size. The bulbils tolerate desiccation, are dormant during the summer and are dispersed by wind and ants. Both the basal bulbs, which are also dormant during the summer and the inflorescence bulbils sprout at the peak of the winter rainy season (cf. Ofir and Kigel 2014).

Two varieties are distinguished in the flora. Plants with bulbils in the inflorescence are recognised as Poa bulbosa  var. vivipara  Koeler, Descr. Gram. 189. 1802 [Type: "prope Moguntiam in arenosis"; Poa bulbosa subsp. vivipara  (Koeler) Arcang., Comp. Fl. Ital. 785. 1882; Paneion bulbosum var. viviparum  (Koeler) Lunell, Amer. Midl. Naturalist 4: 222. 1915; Poa bulbosa f. vivipara  (Koeler) Maire, Fl. Afrique N. 3: 86. 1955], a variety distributed in Europe, Africa and SW, C and N Asia to W China and introduced in the Americas, Australia and the Pacific Islands; it appears in practically all of the provinces of Flora iberica [And. Port.: AAl BAl BB BL E TM. Spa.: A Al Ab Av B Ba Bu Ca Cc CR Co Cu Ge Gr Gu H Hu J L Le Lo Lu M Ma Mu Na Or P PM[Mll] S Sa Sg Se So SS Te To V Va Vi Z Za], from sea level to 3100 m, with a preference for shady places. The other variety, Poa bulbosa  var. bulbosa  [ Poa crispa  Thuill., Fl. Env. Paris, ed. 2: 45. 1799, type: "Habitat in locis arenosis. Floret Maio"; P. pasqualii  Heldr. ex Parl., Fl. Ital. 1: 343. 1850, nom. inval., pro syn.; P. bulbosa subsp. perligulata  H. Scholz, Bot. Chron. 3: 17. 1983, Typus: "Italia: Insula Elba, marina di Campo, 12.4.1980, W. Lang w.n. (B)"; P. perligularis  H. Scholz, Willdenowia 16: 404. 1987, non Poa perligulata  Pilger, Notizbl. Bot. Gart. Berlin-Dahlem 11: 779. 1933; P. bulbosa f. variegata  Font Quer, nom. nud., in sched. (MA 11272), syn. nov.; P. bulbosa f. minor  H. Villar, nom. nud., in sched. (MA 156764, MA 156765), syn. nov.], is distributed throughout the range of the species and comprises plants in which the spikelets produce normal flowers; this variety is found mostly in provinces covered by Flora iberica [Port.: Ag AAl BAl BA BB BL DL E Mi R TM. Spa.: A Al Ab Av (B) Ba (Bi) Bu C Ca Cc (Cs) CR Co Cu Ge Gr Gu H Hu J L Le Lo Lu M Ma (Na) Or O P PM[(Ib) Mll (Me)] Po S Sa Sg Se So (SS) T Te To V Va Vi Z Za], where it ranges from sea level to 2895 m and generally thrives in exposed places.

Bulbs appear to have arisen in Poa  at least twice and possibly as many as four times ( Cabi et al. 2016). Taxa having bulbs are distributed in four clades: (1) P. supersect. Poa  ( P. densa  Troitsky and P. diversifolia  (Boiss. & Balansa) Hack. ex Boiss; (2) in or near P. supersect. Homalopoa  ( P. pseudobulbosa  Bor); (3) N-clade ( P. pelasgis  H. Scholz); and (4) P. subgen. Ochlopoa sect. Arenariae  (type: P. bulbosa  ) mixed with species of P. sect. Alpinae  (type: P. alpina  ).

In Sierra de Mariola (Alicante), a population has been detected (MA 752991) in which the ligule of the upper leaves in some individuals is very short (1-1.5 mm), subtruncate and irregularly dentate or not.