The Cinderpearl is a new type of plant, introduced in Thaumcraft 3. It only grows in Desert biomes and emits a feeble light.
It drops Blaze Powder when you break it. To collect the flower instead, use the Shears. However, it cannot be put in a Flower Pot.
"Found only in the hottest of places, these plants burn with elemental fire. They can be harvested and ground to produce a fine powder akin to Blaze powder."