Yep, see what I did there? It's true though, thistles are crazy. There are a ton of them, and as far as I can tell, when you get down to the tribe (and sub-tribe), there isn't a definitive agreement even on how many there are, much less what they're called and how the genera are sorted out.

I'm going to break down a few, but leave the bulk to someone who's much better equipped. My primary goal here is to be able to identify common, edible, non-native plants. There are some common non-native thistles that are easy enough for me to ID.

Harvesting: when harvesting these thistles, I will also attempt to reduce their population, so I'll actively trying to remove the plant. To do so, I will remove all of the above-ground growth, and at least two inches of the top of the root. (Also, I'll wear gloves, and have heavy collecting bags to protect myself from the spines.)

Identification: Spiny, Purple, Discoid

The thistles we're identifying here all have spiny leaves and purple discoid flowers (that is, they're aster family flowers with only disk flowers present, no ray flowers, and no disk flowers pretending to be ray flowers). Note that there are also thistles with smooth leaves, other color flowers, and ray or pseudo ray flowers present. Also, there are a lot of spiny, purple, discoid thistles that are native - keep reading to find out how to separate out the non-natives. I'm breaking out these because they're the most common edible non-natives I see in the Bay Area.

Non-Winged Stems

Cynara cardunculus (artichoke, cardoon) is very large. Its downy leaves reach up to 50 cm (20 inches) long, so the full basal rosette can be almost 4 feet across. The receptacles are 2 or more inches wide (some globe artichokes are considerably larger). The phyllaries (bracts in the receptacle) may have short spines on the tips (artichokes) or long triangular reflexed spines (cardoon).

Silybum marianum (milk thistle) can be identified by the milk-white variegations in deep green leaves.

Winged Stems

Onopordum acanthium (cotton thistles) has winged leaf stalks, and cottony down all over the plant including the tops and bottoms of the leaves, the stem - including the wings, and the phyllaries.

Carduus and Cirsium have winged stems, but not winged leaf stalks. (Not all Cirsium have winged stems, but the ones that do are not native).

The "True" Thistles: Carduus and Cirsium

These Two genera are usually considered the 'true' thistles. Of the two, only Cirsium has California native species (and it has a lot of them). As far as I can tell, none of the winged stem varieties of Cirsium are native. I will continue to investigate, but for now, I'm equating winged with non-native.

How to tell them apart: the difference between Carduus and Cirsium is in the white hairs attached to mature seeds (pappi). In Carduus, the pappi are simple (unbranched) or minutely barbed. In Cirsium, they are complex (branched). This may also be true for the bracts that make up the phyllaries - but I'm not sure of that yet.

So, What are We Eating:

We're eating spiny leaved thistles with purple discoid flowers that are either:

• huge: basal rosette 3-4 feet across, grey green foliage with large (2 inches or more diameter) receptacles. Cynara cardunculus (artichoke, cardoon)

• Variegated: shiny dark green leaves with milky white lines. Silybum marianum (milk thistle)

• Have winged stems: Onopordum acanthium (cotton thistle), Carduus, and non-native Cirsium species.

Edibility

While not all thistles everywhere are edible, those that fall into these four groups, and occur in California are. They are edible root to tip. I don't have a ton of experience with these, and I have to say, I'm not excited to try the cotton thistle... all that cottony down just turns me off a bit. However, if I see it, I will at least try it.

Recipes

How I'm going to try them first:

• Roots: I'm not sure - I'll have to see them first.

• Leaves - Raw: mid-rib only and de-spined whole leaves. Cooked: de-spined leaves prepared like spinach. If cooked greens are bitter, I'll try parboiling.

• Stems - Raw: peeled stem. Cooked: prepared like asparagus or braised. Preserved: pickled with recipes for pickled asparagus. My sources say the stem always has to be peeled.

• Flowers - Raw: tender young heads alone or in a salad. Cooked: steam and eat (especially Cynara), marinate with recipes for marinated artichoke hearts. Preserved: pickled?

• Seeds: roasted, cracked and boiled, pressure cooked.

My research says that spines need to be removed only if you're eating leaves raw, and if you cook them then they're not a problem. This worries me, but I will at least experiment with it.

Other Uses

Older stalks can be used for cordage - soak for several days and peel the fibrous outer layer. I may try to soak the outer layer from the stems I peel and eat and see if I can use it for cordage. Fluff from the seed heads can be used as a tinder. Extract from the stalks of at least some (Cynara) can be used in place of rennet in cheese making.

While we're near the subject, let's also address three species of non-edible invasive plants. In the subtribe Centaureinae, genus Centaurea there are three species of particularly nasty invasive plants.

Centaurea solstitialis (yellow star thistle), Centaurea melitensis (Maltese star thistle), and Centaurea calcitrapa (purple star thistle) are all relatively easy to identify.

They have spines on the receptacles of the flowers that are particularly long, thin, and tan/brown colored. The first two have yellow flowers, and the C. calcitrapa has purple flowers.

Follow the links on the species names to report your star thistle observation. If you are positive about your identification and chose to take (illegal on public lands) action, the best time to manually pull these plants is after flower stalks emerge, but before seed set. Also, you must remove all of the stem and at least the top two inches of root to avoid regrowth. For more information and photos, see the iNaturalist page here.