IDing plants/lichens
Brooms: https://ipm.ucanr.edu/PMG/PESTNOTES/pn74147.html
Dipsacus (teasels): http://webidguides.com/_templates/group_teasels.html
Lupinus spp.:
- https://tchester.org/plants/analysis/lupinus/identification.html
- https://www.inaturalist.org/journal/leafybye/22229-the-misidentification-of-lupinus-nanus-or-lupinus-bicolor
Mustard: https://www.tchester.org/plants/analysis/mustard/comparison.html
Polypodiopsida (ferns): https://www.worldplants.de/world-ferns/ferns-and-lycophytes-list
Plants in winter: Weeds and Wildflowers in Winter by Lauren Brown
Botanical terminology: Harris & Harris’s Plant Identification Terminology: An Illustrated Glossary
Online Flora
Flora of North America: http://floranorthamerica.org
Flora of the Southeastern United States: https://fsus.ncbg.unc.edu/
List of multiple states' floras on csledge's journal post (halfway down): https://www.inaturalist.org/journal/csledge/55746-a-list-of-online-resources