Common Name: Onion (Garden Onion, Common Onion, Bulb Onion)
Latin Name:Allium cepa
Family Name: Liliaceae
Onions are known to be toxic to cattle, horses, birds, cats and dogs, and several sources say that they are toxic to tortoises and turtles as well, causing digestive problems if eaten in small amounts and more serious illness if eaten in quantity. The toxic principle is n-propyl disulfide, which is also present in garlic, and can cause the rupture of red blood cells.
As it is a general rule that we do not feed plants that grow from bulbs, and given the specific evidence of toxicity in this plant, we recommend that you do not feed any part of the onion plant to your tortoise.
Although most Onions have white flowers, there are varieties with pink, lilac or purple flowers. See Chives.