Yellow Flag Iris

You can see the eponymous golden flowers between May and August, at the edge of the pond. The yellow flag is a marginal plant, so only grows in the shallow water, where it can reach over one metre tall.

The large petals, called falls, have purple veins. Each flower produces a lot of scented nectar which attracts hoverflies and bees, like the common carder bee seen above and below, and on the right with its bottom sticking out of a flower.

In return, of course, the insects adventitiously bring pollen. Once fertilised, seeds will start to form in green capsules, which eventually turn brown and then split to release the brown pea-like seeds.

The plant can soon spread as, besides seeding, its rhizomes also extend underwater. While native to Europe, in some countries, such as the USA, it is red-listed as a non-native, invasive species.

Folk names for yellow flag include Water Skegs, Jacob’s Sword, Swordgrass and Daggers, all alluding to the shape of the grey-green leaves (which are eaten by larvae of the Iris sawfly).

Although not apparently recorded by any Stroudwater clothier, yellow flag was used as a dye for tartans and tweed in the 18th C Scottish textile industry. Depending on the associated mordant, the roots gave black (iron) or blue (copper), while the leaves afforded bright green (alum).

Links to further information and images

The Wildlife Trusts

 

Scottish pollinators

 

Wednesday weed