Perennial Sweet Pea Surprise

When I first moved into my home 4 years ago, the backyard was almost entirely grass. I noticed a little blooming plant in the corner where my backyard met with 3 of the neighboring yards, however. Occasionally, I or my neighbor would nick it with the mower and it would always come back just fine.

When we fenced in the backyard I discovered that the plant is sited in the very corner of my property, so it became part of the "Bordeaux garden." Based on the flowers and the foliage, I had guessed that it was a sweet pea, and therefore deduced that someone must have gardened in that area in the past. The flowers on this pea are a pretty mauve/purple, seen here mingling with a branch of my 'Concord' grape that needs to be cut back since it's obscuring the stepping stone:


This morning I was weeding around the patio stones when I came upon a surprise. Not only was the sweet pea continuing to bloom, but also it was covered with... peas!


My first inclination was to run for the camera, of course, and as soon as a few pics were snapped I headed back indoors to download them and do a little investigation. I was pretty sure it was not actually a sweet pea, lathyrus odoratus, by now, as the flowers are not fragrant and the foliage isn't quite right. This may not be the greatest picture, but I hope you can see how flat the stems are, even where they join together:


A commenter on the Dave's Garden site, in fact, mentioned not liking this plant because its foliage looked like a bunch of preying mantises all strung together... but that's part of what I like about it! This unique foliage helped me to identify my mystery plant as the perennial sweet pea, lathyrus latifolia.

All parts of this plant, including the "peas," are poisonous, and it has been mentioned as being invasive in certain areas as well. So I'm off to cut off the little seedpods now... I'm not going to yank out the plant, but I don't particularly want to enable it to spread around. And with a Gardening Assistant who likes to sample the produce in my yard, I really can't have toxic seeds that look like appetizers hanging around within a dog's reach!