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Commelina ensifolia R.Br. 1810
pronounced: kom-uh-LEE-nuh en-see-FOH-lee-uh
(Commelinaceae — the wandering Jew family)
common names: Scurvy Weed, Wandering Jew
Commelina was named for two 17th century Dutch botanists, Johan Commelin and his nephew Caspar Commelin, who were known to Linnaeus. Johan, also known as Jan Commelijn, was the son of an historian and the brother of a bookseller and newspaper publisher. Johan became Professor of Botany at Amsterdam. He was instrumental in making the Amsterdam Botanical Garden one of the finest of its time. This was a time when hundreds of plants new to Europe were being imported from the Cape and Ceylon, and when Linnaeus was developing his system of plant classification. Commelin cultivated exotic plants on his farm near Haarlem, and made a fortune by selling herbs and drugs to apothecaries and hospitals in Amsterdam and the other Dutch cities. He also took a leading part in the preparation for publication of several important botanical works, but is chiefly remembered for the book Horti Medici Amstelodamensis Rariorum Plantarum Descriptio et Icones, a very comprehensive description, with illustrations, of all the rare and exotic herbs found in the Amsterdam Botanical Garden. He died before the book could be published, and the work was completed and published by his nephew Caspar five years after his death. Ensifolia is from the Latin ensis, a sword, and folium, a leaf – sword-shaped leaves.
For many years I believed this plant to be Commelina erecta, and indeed had identified it as such in this website. There is much confusion about several very similar species of Commelina. The name of C. ensifolia was given to two separate species, first by Robert Brown in 1810, and later by von Mueller in 1872. Von Mueller’s plant proved to have been earlier described as C. erecta. The flowers of both species are very similar, but C. erecta’s blue petals are more stalk-like at their base. C. cyanea also has similar flowers, but the smallest, lower petal is the same blue as the larger, upper ones.
The plant is an Australian native, and is found in all mainland states except Victoria, in monsoonal forest, riparian forest, various types of woodland, and wooded grassland.
The stems of Commelina ensifolia are more-or-less prostrate, producing roots at the nodes. The stems are longitudinally ribbed, and are clothed in pale hairs. The leaves are semi-fleshy, their blades 45-100 by 8-30 mm, with a sheathing petiole about 15 mm long. The blades are covered in fine pale hairs.
The ephemeral flowers, about 2 cm or a little more across, have two larger, showy blue petals, 9–10 by 11-12 mm, and one much smaller petal, 3–4 by 3 mm, that is either very light in colour or translucent. The two larger blue petals are ear-shaped, and the flowers emerge from a folded bract that is fused near the base, and remains folded after the flower withers. The flowers wither the day after they open, often before midday, but there are several buds on a plant, and they open 3 or 4 days apart. There are 3 stamens: one central stamen with a non-versatile anther on a short filament, and 2 lateral stamens with versatile anthers on long filaments, that hang down below the petals and flank the long style. There are also 3 staminodes with cruciform anther parts, clustered around the central anther, that serve to mislead the pollinating insect into believing that there is more pollen on offer than is actually the case – there is no nectar produced to attact pollinators. If no pollination is effected by visiting insects, the style will curl back upon itself, hoping to trap some pollen on the way, in order for the flower to self-pollinate.
The fruit is enclosed in a large bract.
Photographs taken at Picnic Bay 2009
Page last updated 1st November 2016