Identificaciones de w_mark_c

(Eastern) False Rue-anemone - Enemion biternatum (syn. Isopyrum biternatum)
Location: Durham County, NC (USA)
Quite a rarity in this area.
Blooming at this site, 27 March 2021:
www.inaturalist.org/observations/72900244

Smooth Alder - Alnus serrulata (in bloom)
Seems to be our only alder species in the Piedmont. The staminate (male) catkins dangle from the twigs. On some twigs, there are obvious short cone-like clusters of reddish pistillate (female) catkins. I had not noticed the latter in their fresh state previously.
Donald Stokes, one of my favorite nature writers, notes:
"[Female catkins] are small and shaped like miniature pine cones. When they are in bloom, minute reddish hairs project from them in all directions to help catch the pollen grains out of the air. The female catkins are usually found immediately above the male catkins."
References

• Radford et al., Manual of the Vascular Flora of the Carolinas (UNC Press, 1968), p. 366
• Stokes, The Natural History of Wild Shrubs and Vines (Globe Pequot, 1989), pp. 32-36
• Weakley, Flora of the Southeastern United States (UNC Herbarium, 2020), p. 829

American hornbeam - Carpinus caroliniana
In bloom, with long clusters of staminate (male) flowers and pistillate (female) flowers barely visible at the tip of the twigs because leaves are already emerging.
I had been photographing a nearby blooming hazelnut and noticed the Carpinus. Yup, it was in bloom too!

American hazelnut - Corylus americana (in bloom before leaves present)
Based on glandular hairs on (many) twigs, this keys out to Corylus americana as opposed to the other possible species, Corylus cornuta (Beaked Hazelnut). Swanson notes an additional useful character not found in other sourcess--stems of staminate catkins in C. cornuta are stalkless, or nearly so, while those of C. americana have longer stalks. Swanson's figure also shows that staminate catkins of C. americana are much longer than those of C. cornuta, but he does not mention this in the text.
References

• Radford et al., Manual of the Vascular Flora of the Carolinas (UNC Press, 1968), p. 366-7
• Swanson, A Field Guide to the Trees and Shrubs of the Southern Appalachians (Johns Hopkins Univ. Press, 1994) pp. 138-9, fig. 27
• Weakley, Flora of the Southeastern United States (UNC Herbarium, 2020), p. 831

A few documentation images from a couple of local birding trips.
White-crowned sparrow - Zonotrichia leucophrys (first winter plumage)
There is a big flock (~50) at this site every winter. Otherwise this is a rather rare bird in the Carolina Piedmont.