Can anyone ID these weeds?

[GotTort]

 

[GeoTerraTestudo]

That's wild prickly lettuce (Lactuca serriola), the closest cousin and possibly the ancestor of all our cultivated lettuce (Lactuca sativa). It's native to Europe, but is now established all over the US. It is edible, and tortoises really seem to like it. However, like a lot of plants, it seems to be more palatable while it's small and hasn't developed bitter-tasting compounds yet. But it's a great tortoise food, and I give it to my guys all the time. They love it!

 

[GotTort]

Thanks cause I've got a lot of it

 

[GeoTerraTestudo]

Excellent!

 

[GotTort]

The tortoise table says prickly lettuce is toxic?

 

[GeoTerraTestudo]

The tortoise table says prickly lettuce is toxic?

I think the Tortoise Table likes to be cautious about the foods they recommend. This could be because there are dietary differences among different tortoise species. I think they might also be going by what's safe for ungulates like sheep, cattle, or horses, even though many tortoises and box turtles are known to eat foods that can make livestock sick (see the thread, "Article: steppe tortoise diet in the wild").

Prickly lettuce does produce latex, which contains oxalic acid. But then, so do a lot of other edible plants. As long as tortoises get a varied diet, it's not a problem. Also, as I mentioned, tortoises and other herbivores often prefer to eat younger plants that have not yet started producing bitter compounds. My Russians love eating young prickly lettuce, but once it gets beyond a certain size, they may nibble on it, but they don't scarf it down anymore, probably because it has become too bitter at that point.

Domestic plants have been bred to be more palatable, which is why cultivated lettuce is simpler than prickly lettuce. Tortoises may enjoy the tame flavor of grocery greens, but it seems that they sometimes want the complexity of wild weeds, too. Cultivated and wild plants can also provide different nutrients in the tortoise's diet. I've found that prickly lettuce is a good way to provide that, at least when it's young.

 

[GotTort]

Thanks. Appreciate the explanation. I agree the tortoise table sometimes seems regarded as the final word when that is not necessarily so.

 

[GeoTerraTestudo]

Thanks. Appreciate the explanation. I agree the tortoise table sometimes seems regarded as the final word when that is not necessarily so.

One thing I did find interesting at the Tortoise Table was its mention of lactucarium, a kind of opiate secreted by uncultivated forms of lettuce. Lactucarium is another compound that plants produce to deter herbivory, but tortoises and other animals can handle it in small amounts. My tortoises will eat prickly lettuce for a while, but then switch to something else. It seems they smell or taste the defense chemicals in the plant, have a certain tolerance for it, or naturally vary their diet to prevent any one compound from building up in their body. The Tortoise Table also mentions that young plants have less lactucarium in their tissues, making them safer and more palatable than older plants.

Prickly lettuce:
http://www.thetortoisetable.org.uk/site/plants_19.asp?mode=main&catID=372

Wild lettuce:
http://www.thetortoisetable.org.uk/site/plants_19.asp?mode=main&catID=574

Lactucarium:
http://en.wikipedia.org/wiki/Lactucarium