Chara globularis stalks and side branches

An interesting green alga, about 100 mm tall, growing on the bottom of the Botanic Garden’s ponds has appeared — it is Chara globularis.

Carolyn Ricci and Bob Baldock from the State Herbarium’s Phycology Unit report that the alga is often found in calcium-rich waters. Its central stalks are ribbed with cells that accumulate lime crystals, and there are rings of stiff side branches ending in points.

Chara globularis, close-up

The female organs are bottle-shaped, wrapped in five twisted cells and stoppered with a cellular plug. Male organs in this species are spherical, lurk just beneath the females and are orange.

Who said that algae are simple life forms?

Botryococcus braunii

This photograph shows a microscopic image of Botryococcus braunii.  Hon. Research Associate Bob Baldock reports that this interesting algae has appeared within floating rafts of filamentous green algae (mainly Oedogonium sp.) in the storagepond of the new Adelaide Botanic Gardens’ First Creek Wetland.

Botryococcus braunii grows as a colony of egg-shaped cells within a tough, gelatinous sheath: individual colonies may cling together by gelatinous strands. Although a member of the green algae, it, and its colonial matrix are usually coloured yellow or brown.  Individual cells store oil droplets, and this feature is currently being researched as a possible source of bio-fuel. — But don’t worry, there is insufficient to set the pond alight!

Bob Baldock is a long-time associate of the State Herbarium of South Australia, responsible for the creation of the Algae Revealed fact-sheet series on marine algae of southern Australia.