Chara is a genus of charophytegreen algae in the family Characeae. They are multicellular and superficially resemble land plants because of stem-like and leaf-like structures. They are found in fresh water, particularly in limestone areas throughout the northern temperate zone, where they grow submerged, attached to the muddy bottom. They prefer less oxygenated and hard water and are not found in waters where mosquito larvae are present. They are covered with calcium carbonatedeposits and are commonly known as stoneworts. Cyanobacteria have been found growing as epiphytes on the surfaces of Chara, where they may be involved in fixing nitrogen, which is important to plant nutrition.
Structure
The branching system of Chara species is complex with branches derived from apical cells which cut off segments at the base to form nodal and internodal cells alternately. The main axes bear whorls of branches in a superficial resemblance to Equisetum. They are typically anchored to the littoralsubstrate by means of branching underground rhizoids. Chara plants are rough to the touch because of deposited calcium salts on the cell wall. The metabolic processes associated with this deposition often give Chara plants a distinctive and unpleasant smell of hydrogen sulfide.
Morphology
The plant body is a gametophyte. It consists of a main axis, dimorphic branches, rhizoids and stipulodes.
Reproduction
Chara reproduces vegetatively and sexually. Vegetative reproduction takes place by tubers, amylum stars and secondary protonemata. The sex organs are a multicellular and jacketed globule or antheridium and nucule or archegonium. The antheridia and archegonia may occur on separate plants, together on the same plant or separately on the same plant. After fertilization, the zygote develops into an oospore.
Species
Distribution
Chara has a cosmopolitan distribution, from 69 degrees north in northern Norway to about 49 degrees south in Kerguelen Islands. About 27 species are found in India. There are about 40 species of Chara in Europe, where they are commonly found in the specific habitat-type designated as H3140 in the Natura 2000 plans of the European Union. Although this habitat is found all across Europe, it is threatened and to be protected and preserved. The Netherlands are home to 20 species of Chara, growing in lakes and ponds of the habitat-type H3140. The H3140 habitats in the Netherlands, are considered important in the overall preservation efforts and therefore also for the Chara species in general. Denmark. Here, many former Chara habitats have been polluted by either toxins or excessive amounts of nutrients, but a few large lakes and ponds remain. Chara is found growing in the very clean hard water lakes of Thy National Park like Nors Sø for example. Tissø lake is also a H3140 habitat and contains Chara species. Ireland:- Co. Galway. Eglinton Canal Chara virgata Kütz., Chara rudis Leonhardii and Nitella flexilis C.Agardh.
