Can a reflexive verb (s'asseoir) be used in a sentence without a reflexive pronoun?

Question

Bonjour,
Is this sentence correct, please? : Elles sont allées dans le jardin, et sont assises sous un arbre.
(They went into the garden, and sat under a tree)
Or, is it necessary to write: Elles sont allées dans le jardin, et se sont assises sous un arbre.
Regards,
Cheryl.

Answer

My thought on this is that you can not leave out the reflexive pronoun because this indicates in your sentence that they sat themselves down. 
If they sat an infant in the chair it would not be reflexive.
 If you se coucher, it is putting oneself to bed, but to put another to bed you drop the se. 
perhaps the experts will be able to confirm this?

Answer

Bonjour Cheryl !

Sue is right :)
"Asseoir" without the reflexive pronoun means "to sit [someone else] down".

If you want to say "they were sitting under a tree" - i.e. they're in that position - you will use the passive voice "elles étaient assises" (they were sat).
But if you want to say "they sat [themselves] down under a tree - referring to the action of sitting - then it will be "elles se sont assises".

Also note that if you used "asseoir" as non reflexive (I sat my daughter down), you will use "avoir" as auxiliary:
"J'ai assis ma fille."

I hope that's helpful!
À bientôt !

Answer

Merci encore Aurélie,
Cheryl

Answer

Merci Sue!
 Aurélie agrees with you; many thanks to both of you,
Cheryl