Small agriculture question

[Arsenic]

On my most recent playthrough i've decided to try to use farming/plants this time. I've noticed on Milkweeds and Nettles that using 'g' to pickup and using the skill [A]griculture to harvest the plant produces different products. Is there any difference between say "Milkweed leaves" and "Milkweeds"?

[Galgana]

Milkweeds are the raw grass-type plant obtainable by harvesting with the agriculture skill.
Milkweed leaves are a raw product of the plant and are obtainable through either threshing with the agriculture skill or picking by hand.

A picked plant will grow back in the same place next year if you don't disturb the tile it occupies (i.e. by building or digging).
The same applies with withered plants, but a harvested plant never regrows unless the map tile data is reset.

The only use for harvested milkweed plants is being threshed to obtain both milkweed leaves and milkweed root.
These products can then be used as ingredients in cooking recipes.
You can grind milkweed root into flour with the agriculture skill, but a container is required to hold the flour.
The leaves can also be used as healing herbs for wound treatment with the physician skill.

The herbalism skill allows you to check what herbal effects your character is aware of. You can check patches of plants on tiles adjacent to you or whatever plants/plant products are in your inventory.
Raw effects usually will persist in cooked foods.
Boiling herbal products separately through the cooking menu often enables additional effects. Boiled leaves and flowers become an herbal beverage, while the roots, seeds and flour retain their product identity.
Boiling can also remove negative effects such poisoning or gut irritation, but you have to be careful when using plants and mushrooms you have not yet identified because some species always remain poisonous.