Allium giganteum (Giant Onion):
The smaller white plant to the left is a Fritillaria, but I am not sure what species.
Cimicifuga racemosa, or Black Snakeroot:
Though the above is a pretty diminutive plant, it has an interesting story. Another common name for this is Bugbane or Bugwort because the plant has natural insect-repellent tendencies. This is actually more true for species of Cimicifuga in other regions. Cimex is Latin for bug (bed bugs are Cimex lectularius) thus the origin for Cimi-. -fuga derives from the Latin fugare, which means repel. Racemosa refers to the flower structure. Flowers that bloom along a single stalk are called racemes.
Iris germanica, or Bearded Iris:
Iris or irid refers to a multiple of colors or a rainbow. Presumably the Latin appellation is due to the variety of Iris colors available.
The word bearded refers to the small hairy strip on the Iris's fall. The fall is the morphological term for the lower three petals. The actual petals are only the upper three. The beard on these falls is essentially a landing strip for pollinators, leading them to the inside of the flower.
Epimedium x rubrum, or Red Barrenwort:
Epi means on or above. Medium, is middle. I'm not aware of the meaning for this Latin name. However, in common names, -wort almost always is a clue to some medicinal or folk use of the plant. While one's first assumption is that the plant is then to be ingested by those who can't conceive is accurate, the historical reason people attributed to such barrenness was a low libido. This was used to cure impotence. The first viagra. It was also used for rheumatism and a potpourri of other ailments. None of those benefits have been scientifically proven.
Aquilegia x hybrida, or Columbine:
Didn't we all learn the word aquiline during SATs or PSATs (or was that just my school?)? It means curving like an Eagle's beak or Eagle-like. Aquilegia thus refers to the long arcing curve of the petals. The common name, Columbine, means dove-like. Aquilegia is a sentimental favorite of mine. It's available in blues, pinks, and a native species has smaller flowers in a deep, salmony orange. Even the hybrids re-seed pretty well and can spread well in the right conditions. Its distinctive foliage is referenced in the name for Meadow Rue, Thalictrum aquilegifolium, which has leaves much like the Columbine.