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May 18, 2012
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Southeastern, New Hampshire
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There are only four yellow flower hawkweeds that are tall and have few to no stem leaves.
But it is still difficult to tell the difference between them.
- Meadow (Yellow) Hawkweed (Hieracium caespitosum): The involucre (bracts below
the flower) is 7.5 - 9 mm long. As can be seen from the pictures, the involucre of this
plant is less than 6 mm. Also, Meadow Hawkweed has abudant short bristles on the front of
the leaves and short prostrate stolon (horizontal, creeping stem).
- King Devil Hawkweed (Hieracium xfloribundum): A hybrid of Hieracium
caespitosum and Hieracium lactucella. Early production of prostrate stolons.
The leave blades are glaucous (covered with whitish or bluish waxy coating) and nearly
hairless on the front. Has 3-30 flowers in a tight cluster on short pedicels.
- Glaucous Hawkweed (Hieracium piloselloides): Flower stalk has few or no
stellate hairs. Stellate hairs are star-shaped hairs with several to many branches
radiating from the base. The backs of the basal leaves are hairless or with simple
non-glandular hairs.
- Tall Hawkweed (Hieracium praealtum): Flower stem has moderate to very dense
stellate hairs (see closeup pictures below). Minute stellate hairs are usually found
on the back of the basal leaves, but I did not see many of those hairs (unless I did
not have great enough magnification).
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