Posted on

weeds with exploding seed pods

This plant’s seed dispersal method is very similar to the one of ruellia tuberosa (cracker plant), which we’ve mentioned earlier in this list.

The dry seed pods of this plant explode when getting in contact with water and seeds are dispersed away from the plant. These are often collected by children as they offer quite a fun show when they start popping one after another.

Once the fruits reach maturity, or when something touches them, they burst open and explosively discharge the seeds inside at impressive speeds. A part of the seeds reach and stick to the neighboring trees, which thus become the host for the next generation of this parasitic plant. Birds also help the spread of dwarf mistletoes to more distant areas.

9. Violets (Viola spp.)

Hairy Bittercress (Cardamine Hirsuta) is an annual or biennial species of plant in the family Brassicaceae (mustard family) native to Eurasia but prevalent in many moist areas of the world. Other popular names for Cardamine hirsuta include shot weed, lamb’s cress, flick weed, land cress, spring cress, and hoary bitter cress.

Ballistic seed dispersal (or ballochory) consists of the plant ejecting the seed(s) with a great force, similar to a small explosion. This process is also known as explosive dehiscence.

Honey Spurge (Euphorbia Mellifera) is an evergreen shrub in the spurge family Euphorbiaceae.

This tree species can grow up to 200 ft (60 m) high but does not only impresses by its size. Sandbox trees also contain highly toxic sap, and can be easily recognized by the many dark and pointed conical spines covering their trunks. However, these trees are especially known for their explosive fruits.

I’ve become fascinated with this weed, at least so far. I’ve more-or-less got it under control in my garden. I really don’t remember it from years ago, but it sure has been a pest the last 5 years or so. Not a native of California, it is now here for the foreseeable future… and beyond. I can’t say it’s the worst weed in the garden, but it sure requires attention to keep it under control. Especially these days when it will be competing for available water.

Hairy Bittercress (Cardamine hirsuta)

If all else fails, Hairy Bittercress is a member of the mustard family and is edible, but you need to do your own research to find the right recipe to enjoy it (for an example, see http://www.eatingniagara.com/2013/04/weed-wednesday-make-that-hairy.html). To get ahead of its persistence in the garden, it’s definitely worth patrolling your garden for this weed once or twice a week during the winter and spring. It’s easy to hand pull when young. Once the seeds pop, you’ll be fighting a much bigger crop next year and it’s rare that herbicides would be considered appropriate for control in a home garden.

Even if you didn’t recognize it outright, maybe you’ve had the experience of being out in the garden pulling winter weeds when you’re pulling what looks like a small “innocent” weed only to find it exploding seeds in your face and all over the nearby garden? The most likely culprit is Hairy Bittercress (Cardamine hirsuta), which starts growing almost immediately with the onset of the late winter rains. It originally looks like a small, flat rosette of small leaves and then in what seems like the next day, quickly produces small white, four-petal flowers on wiry green stems. Most of the problems with this weed can be “solved” if you pull it at this stage or at least before it flowers. Seemingly overnight, the flowers form needle-thin seed pods, which explode at the slightest touch, sending seeds in all directions (averaging around 600 seeds per plant… and the bigger the plant, even more seeds). Besides your garden, the seeds are easily propagated in cracks in flagstone, brick or concrete walkways.

Because Hairy Bittercress thrives in moist conditions and disturbed soil, it is also a pest in nurseries, and can be brought home via plant purchases. If you think that’s a problem for you, some cautious gardeners carefully remove the top inch or two of soil in the pots before planting. (If you do this, you should dispose of the scraped-off soil in your green can.)