Fridays seed – Acanthus hungaricus and the retinaculum

I thought it would be interesting to present the fruit and seed of Acanthus hungaricus this Friday; after all, what’s the fun of going through a bunch of spiny, dry flowering stems without sharing? ;)

The fruit of Acanthus (bear’s breeches) is a two parted capsule with an explosive opening.
The seeds inside the capsule are attached to a stalk called funicular retinacula (retinaculum or jaculator) which helps to propel them outside the capsule. This is, of course, an adaptation for seed dispersal. See the plate below.
In our climate it seems the mechanism doesn’t work to well, or it may happen in very late fall, in any case there are usually very few good seeds formed (I emphasize ‘good’).

The thing is Acanthus may lack its principal pollinator in our region; on the flowering stems I worked with, most of the capsules were empty; just few of them were bearing one seed.
It is very probable that the capsule needs to be full with seeds in order to build enough pressure inside and stimulate the retinaculum to eject them outside (just my theory…).

A mature,  flowering bear’s breeches is absolutely spectacular, like seen in the picture (alas, not in my garden). It takes a few years but I would say it’s worth the wait. Even in the happy event that you will find it at a garden center it will also be a young one.

Here’s one seedling that was planted in the ground last week; I sown 4 leftover seeds in February of this year and now I have 4 seedlings (some bigger than the others).