Three recently-introduced alien grasses in the Iberian Peninsula

Three non-native grasses (Gramineae/Poaceae): Bothriochloa barbinodis, Bothriochloa laguroides subsp. torreyana and Agropyron desertorum, apparently hitherto unrecorded, have been detected in the Iberian Peninsula in recent years, and a further species, Nassella neesiana, is recorded as increasing its known distribution area in Catalonia (NE Spain).

native of the New World (Argentina northwards as far as the southern United States) and in Europe has been detected in the south of France, where it is fast spreading to the north at present.This recent observation, made in the fast-developing Vallès Oriental area quite close to Barcelona, resulted in fresh material being gathered, which was studied with the help of the recent contributions of Jacques Lambinon and Filip Verloove (Verloove & Lambinon, 2008).This population may have arrived from the Hérault (France) by means of rail or road transport.Due to the complexity of the B. saccharoides group of species, it is placed here as B. barbinodis pending confirmation by an expert in the group at a worldwide level.
Bothriochloa is a taxonomically complex genus.It is not surprising therefore that the identity of its representatives in Europe remained unclear until recently.The presence of B. barbinodis in Europe, for instance, was finally confirmed by Lambinon (1995).This plant, whose basionym is Andropogon barbinodis Lag., later reduced to varietal level by Hackel -A.saccharoides Sw. var.barbinodis-, was erroneously referred to as Bothriochloa imperatoides (Hack.)Herter (Auriault, 1975) and Dichanthium saccharoides (Sw.)Roberty (Kerguélen, 1993), both being very similar.It is a From B. ischaemum (L.) Keng it is easily distinguished by its stouter, taller culms with clearly bearded nodes, the presence of a central axis 50-90 mm long in the inflorescence, and by its longer awns: (15)18-25(30) mm, as opposed to (8)10-15(17) mm in B. ischaemum.

Notes breus
From B. bladhii (Retz.)S. T. Lake it differs in its whitish densely soft-hairy inflorescence (silvery-red or purple and scarcely pilose in B. bladhii) and its longer awns (those of B. bladhii and B. ischaemum being about the same length).
From B. insculpta (Hochst.ex A. Rich.) A. Camus, it can be separated by its tall, erect growth habit (B.insculpta tends to be prostrate to ascending, and of a more straggly appearance), the bearded nodes (best seen on fresh material), its longer central axis (0-30 mm long in B. insculpta), and the longer (4.3-7.3 mm) sessile spikelets, these being the fertile ones.
The sterile (pedicellate) spikelets are shorter than the fertile ones in B. barbinodis and its close relatives, but in B. insculpta, B. ischaemum and B. bladhii they are of equal length or longer.
For comparison with other closely related species which might enter the Iberian Peninsula, see Verloove & Lambinon (2008), and also Vega (2000).Other species in the B. saccharoides complex also possess barbed nodes; an identification on this sole character could turn out to be unreliable.
Another taxon in this closely-related group (easily confused with B. barbinodis and its relatives of the saccharoides complex).The species is known to occur in south-east France and Italy (Verloove & Lambinon, 2008), and is native to southern North America and sub-tropical South America.Subsp.torreyana is basically a North American plant, whereas subsp.laguroides is more widely distributed.
The presence of this plant in Torrejón could possibly be explained by the use of this air base by the United States Air Force for many years during the latter half of the twentieth century.It is particularly common in the drier parts of the interior of the southern States, including Texas, and northern Mexico.
The population was first detected in 1994, and appeared to be well established on revisiting the site in 1997.Due to uncertainties as to its identity, it was left unresolved until the discovery of B. barbinodis, which differs from its sister species principally in its more robust habit, its clearly bearded nodes (with hairs 1-4 mm long), and the sessile spikelets, which are approximately 4.5 mm long (ca. 3 mm in B. laguroides).
Hs, (Zaragoza) Zaragoza, San Juan de Mozarrifar, uncultivated ground near Ciudad de Transporte, XM7820, 240 m, 10.08.2010, S. Pyke 6420 (BC 874223).This useful arid-region forage grass has probably made its appearance in Aragón, in the heart of the Ebro Valley, due to the sowing of road and railway embankments in recent years.
With a rapidly-expanding transport network the arrival of a non-native and extra-regional flora is inevitable.This species in particular, though apparently rare at present, could well establish itself in the area since its natural range and habitat coincide with conditions in the Ebro depression, and its preference for clay soils means that it should find the local clay "margas" perfectly suitable.
The collected specimen can be placed satisfactorily within the present-day limits of A. desertorum.However, the much-reduced awns, lemmas that are slightly larger than usually stated for the species (6-7 mm as opposed to 5-6 mm) and glumes with short awns up to 2 mm long rather tend towards A. fragile-A.sibiricum when using traditional keys.On the other hand, the specimen agrees with A. desertorum in leaf width (less than 3 mm), glume shape, and spike dimensions, and the clay soil where it was found growing agrees with its stated soil requirements (the other species grow on sandy ground).
Roshevitz, according to Nevski's herbarium note, described a plant he provisionally named Agropyrum desertorum var.muticum, which logically could be our plant, but I have not seen the type, and Nevski preferred to include this taxon within the synonymy of his Agropyron fragile complex.In my opinion, the presence or absence of awns should not be given too much importance, because there is a lot of variation in closely related genera like Elymus L., Thinopyrum Löve, etc., and breeding for agricultural purposes can easily affect such a character.
Agropyron desertorum is a Eurasian grass (W and C Asia, E Europe) known to be used in seed mixtures for revegetation of disturbed ground such as mining exploitations, rail and road verges, etcetera, and it shares this purpose with another species, Agropyron pectiniforme Roem.& Schult., which has also been introduced into the country.For notes on this and our native Agropyron imbricatum Roem.& Schult.(A. cristatum subsp.pectinatum auct.pl.hisp.), a gypsum-loving species, see Pyke (2008).For these two grasses, the specific level appears to be justified and is here proposed.A further record of this plant, this time from the province of Barcelona and within the capital, is here made and, to my knowledge, this record extends the known localities of this hitherto confused taxon towards the south of Catalonia.The population recorded here is well established and appears to have occupied this site for many years, but only a recent detailed survey of the vegetation of Montjuïc carried out by staff of Barcelona's Institut Botànic at the petition of the city council helped us come up with this surprising find.The grass is not easy to detect except at anthesis.
The earliest known record of the species in Catalonia (from Santa Pau, Girona, BC606450) dates back to 1971.Apart from the other records from the province of Girona (Verloove, 2005), this alien species has also been recorded from Coimbra (Portugal) and Madrid under the names Stipa setigera and Nassella mucronata (see Verloove, 2005).Outside the Iberian Peninsula, it is present in southern France, Corsica, Macaronesia, Italy, South Africa and Australia.It is native to South America.