Subjunctive Stems

Subjunctive stems are irregular stems that apply to the present indicative yo form and all present subjunctive forms.

Subjunctive stems are strong stems in the sense that they always override Boot and Gerund stems where they overlap.

All -cir verbs have Subjunctive stems derived by changing the final c in the stem to zc (conduc· + ir -> conduzc· + a). All -cer verbs follow the same pattern except cocer, torcer, mecer, ejercer, convencer, hacer, and satisfacer.

Here is a list of model verbs with Subjunctive stems:

Model Verbs with Subjunctive stems

Verb	Subjunctive Stem
ser	se·a
haber	hay·a
tener	teng·a
ir	vay·a
decir	dig·a
hacer	hag·a
ver	ve·a
venir	veng·a
poner	pong·a
oír	oig·a
conocer	conozc·a
saber	sep·a
salir	salg·a
traer	traig·a
conducir	conduzc·a
bendecir	bendig·a
caer	caig·a
valer	valg·a
caber	quep·a
lucir	luzc·a
erguir	yerg·a
roer	roy·a
yacer	yazc·a
asir	asg·a

Subjunctive stem reference table

Pronoun	Tense	Ending
yo	Present	o
yo	Subjunctive	a
tú	Subjunctive	as
él	Subjunctive	a
nosotros	Subjunctive	amos
vosotros	Subjunctive	áis
ellos	Subjunctive	an
él	Imperative	a
nosotros	Imperative	amos
ellos	Imperative	an