Compare two Blue Nightshade species:

Blue/Bluewitch Nightshade, Solanum umbelliferum: (the only species at Edgewood)
Leaf: 1-4 cm, elliptic to (ob)ovate, generally entire
Flower: calyx 3–3.5 mm; corolla 16–25 mm wide, lavender to blue-purple, lobes < tube, each with 2 greenish spots at base; anthers 3–5 mm

Chaparral (Purple) Nightshade, Solanum xanti:
Leaf 2–7 cm, lanceolate to ovate, ± entire to 1–2-lobed at base; base obtuse to subcordate
Flower: calyx 4–5 mm; corolla 15–30 mm wide, dark blue or lavender, lobes < tube; anthers 4–5.5 mm