 One of the biggest problems in small impoundments or ponds are weeds, aquatic vegetation. Today we'll be discussing luigia, which is a very invasive species that can be hard to control. Down here we have a primrose species. Over here is redwood luigia. This is smartweed. And then we have alligator weed. Now alligator weed is the most invasive of all of these. That's going to be your major problem. Alligator weed can be confused with these other plants. The one thing to tell alligator weed apart from all the others is a white flower that can be seen on the very top of the plant. Alligator weed also has hollow stems, which you can break apart and see. Smartweed, which is close to alligator weed, the leaves are different. The leaves come down to the stem and wrap around the stem. Alligator weed, this does not happen. The leaves on alligator weed also grow opposite. The leaves on smartweed do not grow opposite. They grow alternate. Over here we have two species of aquatic water primrose. This species is the larger form. This species is a smaller form. This large water primrose also has alternate leaves. And even though the flowers are a bit fragile, their petals are usually yellow as opposed to the white alligator weed. This species also has a filled-in stem, whereas the alligator weed has a hollowed stem.