He is also author of the popular natural history website called Wayne's Word: An Online Textbook Of Natural History, including four decades of lecture material placed on blackboards and whiteboards during his teaching career.
He has studied and photographed duckweeds extensively in California (subfamily Lemnoideae), including the world's-smallest flowering plants, and wrote the duckweed section for The Jepson Manual: Vascular Plants of California (2nd edition).
Armstrong's special areas of interest include: the taxonomy of duckweeds, lichen symbiosis, the fig and its symbiotic wasp, drift seeds and fruits that float across oceans, botanical jewelry and the coconut pearl hoax, poison oak immune response, amazing plants (botanical record-breakers), California floristics (including Brodiaeas in California), and the evolution and adaptations of organisms.
[3] Although primarily a botanist, he has once again focused his attention on ant diversity, his childhood passion.
He is a professor emeritus in the Life Sciences Department at Palomar College, San Marcos, California.