Rhubarb, a perennial easy-grow garden favorite in temperature and cold climates, has fibrous greenish red stalks similar to those of celery and dark green leaves that are beautiful - and poisonous. Only rhubarb's stalks are edible, Sweet strawberries are a traditional and pleasing foil to the rhubarb's tartness.
Exposed to warm water, yeast will begin to foam and expand with leavening power. Do not use boiling water; it will kill the yeast. You can add a bit of the recipe's sugar to the yeast as it dissolves to encourage foaming, but never add salt directly to yeast - it too will reduce the leavening ability.