Below is the textbook description of a impossible to kill plant.
The plant is known as Perennial Sweet Pea or Lathyrus latifolius.
I found this at Dave's Gardens.
Calaveras wrote the following:
On Sep 29, 2008, Calaveras from Kittanning, PA wrote:
HELP ME KILL THIS PLANT! I desperately need your advice. It has taken over a full acre of woodland in the Sierra Nevada mountains of California and is spreading at perhaps 1000 square feet per year. This is at 2800' elevation, with no rain between April and November, on a slope with a low water table, daily temperatures regularly reaching 100F, and full to partial sun. In a few years it will consume the entire property. Burning is risky in this habitat in the season when the plants are exposed. Is there an herbicide that would be effective? It's way past trowel work. Please reply before an air tanker is required. Thanks!
On May 22, 2008, girlndocs from Tacoma, WA wrote:
This sweet pea grows in the neighborhood and established itself in a crack in the sidewalk by our front porch.I let it grow -- even mowing around it when I cut the grass. I don't think I've ever deadheaded it and I only collected seeds once when they happened to be ripe as I walked by. Nevertheless it's only made about 5 "babies" in 7 years. Each year it would grow to cover about 4' square feet in a loose tumbling mass before frost nipped it back.The only places I've seen it really take over are abandoned spots in alleys and so forth.It sure is tough, though. This year a lawn service both mowed and power-edged right where it was springing up and I thought it was the end, but two weeks later it was back. Now I've moved it to a wire fence in the back of my garden that hides my compost piles.
As you can see this is a very hardy plant. In the first story Perennial Sweet pea has no water for the hardest parts of the year with temperatures often at 100oF.
I recommend planting this plant if you have a lot of room to let it take over and said space is hard to get other things to grow on. On the other hand, if you just love sweet peas then just go right ahead and let it take over a large area, because I have seen them take a lot of abuse. I have also heard that old varieties (Like the ones we sell at Life Seed Co and those are Perennial Sweet Pea, and an annual one called old Spice mix, which is a mix of multi colored heirlooms.) have a lot of fragrance to them.
Have you grown Sweet Peas before? How did they do for you? Were they invasive and would you recommend planting them?