Oxford Latin Dictionary:
amygdalites ~ae, m. A kind of euphorbia, broad-leaved spurge.
Pliny the Elder, 26, 8, 44, § 70: alii ἀμυγδαλίτην a similitudine... , "Others call it amygdalites from its similarity [to the almond]."
(A spurge is a weed of the genus Euphorbia, having a milky juice and flowers with no petals.)