The Allen and Greenough is still under construction;
so some links may not work quite the way you would expect.
259. 1. Verbs of the First Conjugation are formed
directly from á-stems,
regularly with a transitive meaning: as, fuga, flight; fugáre, put to flight.
2. Many verbs of the First Conjugation are formed from o-stems, changing the o- into á-. These are more commonly transitive:
-áre, to incite, from stimulus, a goad (stem stimulo-).
- aequó, -áre,
to make even, from aequus,
even (stem aequo-).
-áre, to pass the winter, from híbernus, of the winter (stem híberno-).
- albó, -áre,
to whiten, from albus,
white (stem albo-).
- pió, -áre,
to expiate, from pius,
pure (stem pio-).
- novó, -áre,
to renew, from novus,
new (stem novo-).
- armó, -áre,
to arm, from arma, arms
- damnó, -áre,
to injure, from damnum,
injury (stem damno-).
3. A few verbs, generally intransitive, are formed by analogy from
consonant and i- or u-stems, adding á to the stem: - [The type of all or
most of the denominative formations in §§ 259-262 was inherited,
but the process went on in the development of Latin as a separate
-áre, to watch, from vigil, awake.
- exsuló, -áre,
to be in exile, from exsul,
- auspicor, -árí,
to take the auspices, from auspex (stem auspic-), angur.
- pulveró, -áre,
to turn (anything) to dust, from pulvis (stem pulver- for pulvis-), dust.
- aestuó, -áre,
to surge, boil, from aestus
(stem aestu-), tide, seething.
- levó, -áre,
to lighten, from levis (stem levi-), light.