Acta Botanica 1-2015 - za web.indd ACTA BOT. CROAT. 74 (1), 2015 159 Acta Bot. Croat. 74 (1), 159–164, 2015 CODEN: ABCRA 25 ISSN 0365-0588 eISSN 1847-8476 Short communication Echinochloa colona (L.) Link (Poaceae), a new species in the fl ora of Croatia DARIO HRUŠEVAR1*, BOŽENA MITIĆ1, DUBRAVKA SANDEV1, ANTUN ALEGRO2 1 University of Zagreb, Faculty of Science, Department of Botany with the Botanical Garden, Marulićev trg 9 a, HR- 10000, Zagreb, Croatia. 2 University of Zagreb, Faculty of Science, Department of Botany with the Botanical Garden, Marulićev trg 20/II, HR- 10000, Zagreb, Croatia. Abstract – During fl oristic research into the eastern parts of Mt Medvednica (NW Cro- atia), in the period from 2007 to 2010, the neophyte taxon Echinochloa colona (L.) Link was found. Since E. colona is not included in plant identifi cation handbooks, a new deter- mination key for the two closely related taxa of genus Echinochloa, presented in Croatia, has been prepared, and the biology of this new alien plant is briefl y discussed. Keywords: Croatia, Echinochloa colona, Medvednica, neophyte, new species Introduction The genus Echinochloa Beauv. includes about 50 species that are widespread in both tropical and temperate regions of the world in dry or water-fl ooded soils (YABUNO 1966, MICHAEL 1983). The most widespread species of the genus are Echinochloa crus-galli (L.) P. Beauv. and Echinochloa colona (L.) Link (YABUNO 1983), two of the worst weeds in crop fi elds (HOLM et al. 1977). Echinochloa colona (L.) Link (name accepted from MICHAEL 2009) is a grass plant native to India and now widespread, especially beyond 30°N and 30°S latitude (MICHAEL 1983). As a cosmopolitan weed, it is known under many synonyms: Panicum colonum L., Syst. Nat. ed. 10, 2: 870 (1759); Milium colonum (L.) Moench, Meth- odus: 202 (1794); Oplismenus colonus (L.) Kunth in F. W. H. von Humboldt, A. J. A. Bon- pland and C. S. Kunth, Nov. Gen. Sp. 1: 108 (1816); Echinochloa zonalis (Guss.) Parl., Fl. Panorm. 1: 119 (1839); Brachiaria longifolia Gilli, Ann. Naturhist. Mus. Wien 69: 39 (1966) (CLAYTON et al. 2002) and common names: jungle rice, little barnyard grass, corn panic grass, Deccan grass, jungle rice grass, millet rice, southern cockspur, swamp grass (CABI 2012). In Europe, the species is established in France, Greece, Italy, Spain, Cyprus, the European part of Turkey and on the Mediterranean islands like Balearics, Corsica and * Corresponding author, e-mail: dario.hrusevar@biol.pmf.hr Copyright® 2015 by Acta Botanica Croatica, the Faculty of Science, University of Zagreb. All rights reserved. HRUŠEVAR D., MITIĆ B., SANDEV D., ALEGRO A. 160 ACTA BOT. CROAT. 74 (1), 2015 Sicily (PIROLA 1965, DAISIE 2012). According to NOBANIS (2012), the species is also known from Sweden, where it was fi rst recorded in 1924 and it is listed in the fl ora of Czech Re- public as a casual neophyte (PYŠEK et al. 2012). Materials and methods Study area Mt Medvednica is 42 km long and approximately 9 km wide (POLJAK 2007), stretching in a NE-SW direction in northwest Croatia, in the Continental biogeographical region (cf. RADOVIĆ et al. 2009). Here, on only 0.4% of state territory, 1,205 taxa are present, which represent 22% of total Croatian fl ora (NIKOLIĆ and KOVAČIĆ 2008). In order to protect the fl ora and vegetation, especially the forest habitats, Medvednica Nature Park was proclaimed in 1981 and currently covers an area of 17,938 ha (ANONYMOUS 2009b). The researched area (Fig. 1), which is heavily anthropogenically infl uenced, occupies 5.5 km2 outside the Na- ture Park’s borders. It is located between four settlements – Čučerje on the West and Vu- grovec on the East, the northern border is the road via Goranec which connects two places mentioned above, and the southern border is near Šimunčevec. Although the massif is mainly built of Palaeozoic and Triassic metamorphic rocks (predominantly green schist) (ŠIKIĆ 1995), the study area is characterised by carbonate and dolomite bedrock covered with limestone-dolomite black soil (kalkomelanosol) and brown soil on the limestone and dolomite (kalkokambisol) (ANONYMOUS 2011). According to the climate classifi cation by Köppen, Mt Medvednica belongs to the temperate C climate (warm-temperate rainy cli- Fig. 1. Upper left corner – position of Mt Medvednica in Croatia. Larger image – Medvednica Nature Park is marked with black line and the studied area is indicated as a white oval circle. ECHINOCHLOA COLONA IN CROATIA ACTA BOT. CROAT. 74 (1), 2015 161 mate – Cfb) (BERTIĆ et al. 2005) with 1,238 mm of annual precipitation on Sljeme (NIKOLIĆ and KOVAČIĆ 2008). Plant identifi cation and mapping Plant identifi cation was done by using relevant the determination key for European vas- cular fl ora (CLAYTON 1980) and checked again by two additional keys (MICHAEL 1983, FEL- GER 1990). Collected plant specimens were deposited in the Zagreb Herbarium (ZA). Geoc- oding of the site was performed with the use of a GPS device. Results and discussion A small population of Echinochloa colona with fewer than ten individuals was found in the area of Vugrovec (45°52'52.49"N, 16°06'25.41"E). Plants were grown in the ditch alongside the road, in the edge of crop fi eld, mixed with other ruderal species such as Arte- misia vulgaris L., Ambrosia artemisiifolia L. and Festuca arundinacea Schreb. After being recorded for the fi rst time in the area of Mt Medvednica (HRUŠEVAR 2009), the species was also recorded in Zagreb (BASTIJANČIĆ 2010). Even though the continental climate of Croatia is not quite suitable for E. colona, special attention should be given to its potential to be- come naturalized, especially should it occur in the Mediterranean region, where it could become invasive. It is also possible that E. colona was misidentifi ed in previous research, due to its similarity with some unawned varieties of E. crus-galli (MICHAEL 1983). Until the fi nding of E. colona, there was only one barnyard grass species occurring in Croatia: Echi- nochloa crus-galli. This species is well known weed and common grass in the fl ora of Croatia (HULINA 1998, NIKOLIĆ 2012), where it forms the alliance Panico-Setarion Sissingh in Westhoff et al. 1946 (ANONYMOUS 2009a). According to MAREKOVIĆ et al. (2009), it is the second most widespread grass species in Medvednica Nature Park. Even though E. colona and E. crus-galli are hexaploids, they differ in genome constitution so their F1 hybrids are sterile (YABUNO 1962). Echinochloa colona (Fig. 2) is an annual or occasionally perennial grass, up to 60 cm high. Culms are stout, usually reddish-purple, erect, ascending or decumbent, often branch- ing from the base, and rooting at the lower nodes. Sheath is 3–7 cm long, compressed, keeled and glabrous. Ligule is absent. Leaf blade is light green, sometimes with transverse purple bands, fl at, glabrous, elongate, 4–10 cm long, 3–8 mm wide, with occasionally sca- brous margins, apex is acute. Panicle is erect or nodding, green or purple-tinged, 5–15 cm long. Racemes are numerous, 2–4 cm long, spreading, ascending, sometimes branched, the lower ones up to 1 cm apart, the upper ones crowded. Spikelets are green tinged with pur- ple, crowded, arranged in circa 4 rows, about 3 mm long, rarely with a short point up to 1 mm long. First glume is 1.2–1.5 mm long, 3-nerved, nearly half as long as the spikelet; second glume is 2.5-3 mm long, 7-nerved; the fi rst lemma is similar to the second glume, fi rst palea ovate, circa 2 mm long, glabrous; second lemma, broadly ovate, circa 2 mm long, glossy. Caryopsis is whitish, broadly ovate, 1.7–2 mm long, fl at on one side, convex on the other (WAGNER et al. 1999). Chromosome number is 2n = 6x = 54 (YABUNO 1962). E. colona inhabits cultivated areas, waste grounds, ditches and fi elds (CABI 2012), from sea level to the height of 2000 m (HOLM et al. 1977, LAZARIDES 1980). We supposed that jungle rice was introduced with the import of crop seeds or with the transport of soil, which is possible due to the signifi cant human impact in the researched area, such as traffi c, agri- HRUŠEVAR D., MITIĆ B., SANDEV D., ALEGRO A. 162 ACTA BOT. CROAT. 74 (1), 2015 cultural and construction activities. One plant of E. colona can produce from a few thou- sand (HOLM et al. 1991, CHAUHAN and JOHNSON 2010) to more than 40,000 seeds (MERCADO and TALATALA 1977). The fl owering period starts 3–4 weeks after germination, quickly fol- lowed by fructifi cation. The fi rst seeds mature 45 days after fl owering. The minimum, opti- mum and maximum temperature for germination temperatures are 15, 30 and 40 °C (URE- MIS and UYGUR 1999). It propagates mostly by seeds but also vegetatively, by rooting at its nodes. The seeds are spread by farm machinery, in crop seed, in irrigation canals, on the feet, fur, feathers, and skin of rodents, birds, and larger animals, including humans (HOLM et al. 1991). E. colona has a wide ecological niche, it is adapted to full sunlight or partial shade, and grows on loam, silt and clay soils (MANIDOOL1992). According to HOLM et al. (1977), E. colona is associated with 35 crops in more than 60 countries. Determination key for Echinochloa species in Croatia 1. Spikelets 1.5–3 mm, regularly arranged in 4 rows. First glume regularly half the length of the spikelet. Sterile lemma and second glume often with a few hairs or short spines but not beset with harsh spines. Long bristles mostly absent from main axis and branches of infl orescence, occasionally a few scattered along the branches and clustered at the nodes. Anthers purple. Caryopses whitish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Echinochloa colona 2. Spikelets mostly more than 3 mm, irregularly arranged. First glume about one-third the length of spikelet. Sterile lemma and second glume with harsh spines. Long bristles along main axis and branches of infl orescence present or absent. Anthers brown or yellow. Cary- opses brownish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Echinochloa crus-galli Fig. 2. Habitus of Echinochloa colona (photo by Dario Hruševar). ECHINOCHLOA COLONA IN CROATIA ACTA BOT. 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