Some plants have really unusual features.  This edible crop and weed, purslane (Portulaca oleracea), has capsular fruits with a top that 'pops off', so that the seeds are then exposed to weather and wind.  This particular type of capsule is called circumscissile, and for this particular plant is could be that the part that is left below with the seeds functions as a splash cup.  I don't know, but it is not unlikely.  The little black seeds would then splash out of the cup when a raindrop hits the cup, and disperse further than just normal falling down out of the capsule. (Note to myself, research needed!)   

Splash cups are not that common, but also occur in the bird's-nest fungus. While looking up purslane I found out that one plant can produce more than 240 000 seeds per season.  Well, it is good it is edible then.

You can read more about purslane and this photo here. 

Photo credit (c) Arjo Vanderjagt on Flickr

Species: purslane (Portulaca oleracea, Portulacaceae)

Species: Yarrow and nosebleeds

The weed yarrow is a native here in the US, but it is also present in Asia and Europe.  It has been used medicinally for a long time.  Its botanical name, Achillea millefolium (Asteraceae), is of course after the Greek god Achilles, and millefolium after a 'thousand leaves' since the leaves are so finely dissected. 

When I was a kid in Sweden, they told us stories how in the old times, school kids would take a piece of the leaves, which have sharp tips on each little leaflet, and put it in their nostrils before a boring class at school.  A while in during the lesson, the kid would just slightly touch its nose, and a profuse nosebleed would start, and wow, the kids got immediately excused from class.

Yarrow is also cultivated here in the US, so it is one of those weeds that the horticulturalists can't really decide if it is good or bad.  Maybe it is just an interesting plant?

Species: Yarrow (Achillea millefolium, Asteraceae)

[Image from Lindman's Bilder ur Nordens Flora (Swedish), public domain]

What a name: fleabane

fleabane, a photo by Vilseskogen on Flickr.

Gorgeous weed in the sunflower family (Asteraceae) with a very weedy name: daisy fleabane. It is a member of the very large genus Erigeron, and the species is Erigeron annuus. Each white ray and each little yellow dot is an individual flower, so what looks like one flower is actually hundreds of flowers in a head, which is typical for the sunflower family.

It has been used to repel insects (therefore fleabane!), and also for many other medicinal purposes. This photo is from southern New York State, but it is a common weed in most parts of the United States.