What is this wildflower with clusters of very small pink buds which open to white flowers? [duplicate]

Question

We have a lot of these wildflowers in our yard, which grow to be about three feet tall. The stems bush out a little along the main stalk. At the end of the stems are clusters, about 4 inches long, of very small pink buds hanging over. I started seeing them in early summer.

After about eight weeks the clusters began turning white and opening into very small white flowers with yellow centers. The flowers were only open for about a week, and are now seedpods, which have not fallen off. If I open one, I find hard seeds. They have no discernible scent at any stage. When budding, the leaves are dark green, with an area of darker green not far from the stem, and as the flowers go by they become yellow.

I'd like to know what they are for a few reasons:

• Are they allergenic? My husband is allergic to goldenrod, (solidago) and some other wildflowers, and he's uncomfortable now that it's pollen season. If these contribute to that, I'll remove them. If not, I'll leave them alone to finish their life-cycle.

• Are they important to the eco-system, specifically bees and ants? Only a few small bees are hanging around, which makes sense because there's very little pollen, and also because we have a lot of things nearby with bigger flowers and easier access. I know some wild things help ants and are useful for preserving the eco-system, so I don't want to pull them unless they're harmful to anything.

• They're pretty, and I'd like to know what to call them!

We're in Massachusetts, USDA zone 6 (meaning our lowest winter temperatures are about −5 °F, −20.6 °C.)

Edit: Even though it's now been identified as a Polygonum, I changed some pictures to show more detail. If that helps narrow down the variety, that's great, but if not, I certainly don't need it. They all look pretty much the same to me, and I appreciate the help I've received.

Answer 1

As mentioned by @Bamboo, it appears to be one of the polygonums; specifically it looks like Pennslyania Pinkweed (Polygonum pensylvanicum) to me. It's in various places in my yard; is an annual but readily re-seeds, and native to most of the US; one less thing I must rip out. Numerous photos at Discover Life

Also, goldenrod is not usually what causes allergies. It is more likely to be caused by ragweed, which blooms about the same time but has very light, airborne pollen. Goldenrods have heavier pollen, carried by insects. Do a quick google of "goldenrod vs ragweed allergy" for several citations and more information. I pull up all the ragweed I can find, but must wait for it to develop a bit to tell the younglings from some of the annual summer wildflowers (leaves are very similar). Both my husband and I suffer from ragweed allergies, but I've deliberately planted several native species of solidago for the pollinators and nectar seekers.

Hope this is helpful.

Answer 2

It's one of the Polygonums (previously Persicaria, and still listed as such in many references) not entirely sure which, most pics on line are of cultivated varieties, and wild ones are quite variable in appearance, but likely its Polygonum lapathifolium.

These plants are not notorious for causing allergic responses, but every individual is different, and any flower's pollen may cause an allergic response in some individuals. I believe the common name in the USA is smartweed - its knotweed in the UK. As the common names suggest, it's considered a weed - but could equally be called a wild flower.

You may want to remove the seedheads - wild Polygonums are inclined to spread themselves about liberally.

Answer 3

This might be a variety of Pieris japonica. The leaves are throwing me off.

Can you take a few more pictures of the flowers.

Beautiful plant by the way.