Rather than adding observations to projects one by one, here is a another method that allows you to add up to 200 observations at once.

1. Go to your observations
2. Click "Search"

3. Enter Angeles National Forest into "Place" and select plants in "Show only"
   http://screencast.com/t/B1WddT6Af

4. Click "Batch edit"
   http://screencast.com/t/2btas32pNWSH

5. Select All
   http://screencast.com/t/jAA0QdrRfZ

6. Click "Add to project"
   http://screencast.com/t/QJXyOQWa

7. If you have more observations that fits the project's criteria, but are not shown on the page, you'll have to scroll all the way down to get the next link.
   http://screencast.com/t/yBkqfMuz