you can use the ditto mark: "
You might also find that the table looks better if you remove the cell borders and perhaps fill the top row with colour. Or you could differentiate between the plant types by using different font colours - why not experiment?
Tables are the web designer's friend - once you get to grips with tables you'll see that there are all kinds of ways you can precisely control your page content and layout.
Forms are something else - they are for text entry when you want people to submit information, or request something, and the results are either emailed to you, or recorded in a text file on the server, or both.