384 Advances in Environmental Biology, 7(2): 384-390, 2013 ISSN 1995-0756 This is a refereed journal and all articles are professionally screened and reviewed ORIGINAL ARTICLE A New Record of the Invasive Species Hydrilla verticillata (Linn.F.) Royal on the Iraqi Rivers Dr. Fathi A. Al-Mandeel Lecturer Environmental and Pollution Control Research Center University of Mosul, Iraq. Dr. Fathi A. Al-Mandeel; A New Record of the Invasive Species Hydrilla verticillata (Linn.F.) Royal on the Iraqi Rivers ABSTRACT In order to increasing the morphological and anatomical information of exotic species, specimens of Hydrilla verticillata (Hydrocharitaceae) were collected from the little Zab River within Al-Zab area about 90 km from the Kirkuk city. It is a first study that H. verticillata noted on the north Iraqi Rivers. The morphological study showed that the leaves have visible saw-tooth margins and rough teeth on the underside of the leaves.They also have spines along the lower midrib of the leaf which distinguished with reddish in color. In anatomical study, the cross sections through the internodal area of erect stems showed that the aerenchyma consists of lacunae which decreasing in their sizes toward the endodermis. The central cylinder distinguished by non-definiteness xylem tissues, and large lacuna at the center of the stem. Key words: Hydrilla verticillata , Aquatic plants, Plants taxonomy, Invasive plants, Freshwater, Ecology, Iraqi Rivers. Introduction million is spent annually to control aquatic weeds. Additional losses and damages are estimated at In the last 100 years, increasing world-wide around US$ 10 million, giving a total cost of US$ travel and trade has resulted in the introduction of 110 million per year. [22] and [23]. many aquatic plant species to countries beyond their native range, where their subsequent spread has Taxonomy of the Hydrilla: sometimes been extremely rapid [13]. Hydrilla, which is the submerged macrophyte H. verticillata belong to the family native to Australia, Southeast Asia and Africa [25], Hydrocharitaceae [15]. It is the only species in the However it became a cosmopolitan species that genus Hydrilla but several biotypes occur in its occurs in Europe, Asia, Australia, New Zealand, the native range. Some biotypes are monoecious (each Pacific Islands, Africa, Europe, South America, and plant has both male and female flowers) and others North America. Although Hydrilla occurs in are dioecious (each plant bears only male or female temperate areas, it tends to be more widespread in flowers). [9] Hydrilla has the general appearance to tropical areas of the world [18] as well as seen in the the untrained observer of being a dicotyledonous marshes of southern Iraq, Hydrilla was identified for plant, but is in fact classified as a monocotyledonous the first time in the Iraq in 2006 at two locations: plant. [6] Abo Rizk marsh [3] and Al-Chibaish marshes [1]. The latest classification system (known as APG H. verticillata is one of the most serious invasive system: Angiosperm Phelogeny Group system), of aquatic weed Problems. This plant possesses the families and orders of the flowering plants which numerous mechanisms of vegetative reproduction based largely on DNA sequences of the chloroplast, that enable it to spread very rapidly in the nuclear ribosomal, and mitochondrial genes, In this environment in which they live, [6] and extensive system the order Alismatales put in monocot clad growths can severely reduce water flow by clogging (Fig.1) that included six orders addition to the filters of irrigation pumps and trash racks, and Alismatales, which included (13) family along with interfere with boating, water skiing, swimming, Hydrocharitaceae, that the Hydrilla belong to him fishing and navigation. Dense infestations of [5]. Hydrilla can also significantly reduce the holding capacity of storage ponds [27]. According to the Biological and ecological aspects: Office of Technology Assessment, at least US$ 100 Corresponding Author Dr. Fathi A. Al-Mandeel, Lecturer Environmental and Pollution Control Research Center University of Mosul, Iraq. E-mail: [email protected] Tel: +009647705200305 385 Adv. Environ. Biol., 7(2): 384-390, 2013 Hydrilla is a submersed, herbaceous, perennial salinity (five salinity of sea water) more than 7 ppm aquatic plant. It is capable of living in many different [11] it is an important plant that’s grows in a variety freshwater habitats. It will grow in springs, lakes, of aquatic situations: in static water, in water flowing marshes, ditches, rivers, or anywhere there is a few up to 1.8 m /s, and in water from a few centimeters to inches of water. [7], it has the capacity of high 15 m deep [27]. So Hydrilla is widely dispersed, environmental and exceptional ability to adapt in colonizing from tropical to temperate regions (up to different environmental conditions, for this the latitude 53 º N in Ireland) [8]. Hydrilla can thrives in environmental conditions This high capacity to spread resulting from low varying from lentic to lotic, eutrophic to oligotrophic, light compensation and saturation points, and a low acid to alkaline, with high to low light availability, carbon dioxide compensation point, of Hydrilla, that and tropical to temperate climate [16] and it is enabling it to grow in only 1% of full sunlight. [26]. possible to grow up in environments where the Fig. 1: Taxonomy of the H. verticillata according to [5]. In addition, Hydrilla has developed an inducible Hydrilla system represents an archetypal form of C4 C4-acid cycle to combat adverse conditions, such as photosynthesis among angiosperms. [20]. limiting carbon dioxide, high oxygen concentration, As a result of having a C4-acid cycle, it is able high temperature and irradiance. Therefore, Hydrilla to store carbon dioxide in air spaces and as organic can shift between C3- and C4 -type photosynthesis, acids derived from the dark phase of photosynthesis. depending on the environment. It is believed that the This growth habit enables the plant to compete 386 Adv. Environ. Biol., 7(2): 384-390, 2013 effectively for sunlight. [21], for example, once the distinguish it from others, which could be clarified as plant reaches the water’s surface, it will continue follows: growing horizontally across the water’s surface. This growth pattern has the potential to shade other 1 – The leaves: submerged species preventing their growth and establishmen and cause imbalances in pH, Leave characterized by absent of stomata and temperature and dissolved oxygen fluctuations. bright green color but color may bleached by the sun With respect to reproduction of the Hydrilla, It and become yellowish when the leaves presence out has four different forms of reproduction. It can of the water. Hydrilla's leave classified as Iinear- spread by fragments, rhizomes, turions (leaf axis elliptic, serrate, acute. they are strap-like with nodes) and seeds [21], but seed production is pointed tips (terminating in a single strong spine cell probably of minor importance to Hydrilla at the apex). leaves were small about 2-4 mm wide reproduction compared to its successful vegetative and 6-20 mm long, it have saw-toothed leaf margins reproduction. Although seed production and viability and visible spines observed at the tip and along the is low compared to many other weeds [17]. lower midrib. They exhibit a distinct scabrous or The importance of seed production has not been harsh marginal and surface texture (Fig. 2B and C). well researched and is not adequately understood. This spines gives the plant a rough texture. Seeds of many plants can be ingested by birds, The leaves were attached directly to the stem carried for long distances, and passed through the gut and whorled around the nodes in groups of 5 leaves, in a viable condition. If this proves to be true for for this character the species under study named as Hydrilla seed, it may prove to be an important means H. verticillatus, which made up of the Greek word of natural, long distance dispersal. [18]. “hydro” meaning “water” and the Latin word Although H. verticillata discovered in south “verticillus” that means “the whorl of a spindle” Iraqi marshes, The current study is the first that the Appropriately named, it is an aquatic plant with H. verticillata observed in the north Iraqi at a little leaves that are whorled around the stem. [7]. The leaf Zab River. So it aims to increase information about midvein was single, reddish in color and the reddish this species by study of the shoot morphology, as color of midvein is one of the most important well as internal structure of stem. characteristics of the species under study (Fig. 2 A). Hydrilla has an axillary leaf scale called a Materials and methods squamula intravaginalis that is found next to the stem at the base of the leaf. This distinguishes it from the First sampling: other species in the Hydrocharitaceae family. Specimens of H. verticillata were collected 2 - Stems & Roots: from the Little Zab River, which is flow from the northwestern of Iran and extends for a 402 km inside Two types of stems can be distinguish in the Iraq. It is one of the important tributaries that species under this study: are under ground stems entering the Tigris River at northern of Baiji city (Horizontal) and stand stems or Erect (Fig. 3) and the after passing Altoncoopri. final developed from nods that found along the horizontal stems, and growing as vertical axes that Second, laboratory work: support the branches, leaves and reproductive structures. In the present study length of the stem did Included a morphological and anatomical study, not exceed the 30 cm, despite that it is possible grow after the collection of samples directly. For the to several meters [12], stem was a cylindrical shaped investigation of stem anatomy, short pieces of stem and about 0.2 mm, distance between the nodes were cut from the internode of a main stem.