( They ( ( may ( be ( produced ( by ( ( ( asexual or ) sexual ) reproduction ) ) ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (MD may) (VP (VB be) (VP (VBN produced) (PP (IN by) (NP (ADJP (JJ asexual) (CC or) (JJ sexual)) (NN reproduction)))))) (. .)))
They may be produced by asexual or sexual reproduction.
(ROOT (S (NP (NNP Trees)) (VP (VBP send) (PRT (RP out)) (NP (NP (JJ rootlike) (NNS extensions)) (SBAR (WHNP (WDT that)) (S (VP (VBP produce) (SBAR (S (NP (JJ new) (NNS stems)) (VP (VBZ is) (NP (NP (DT an) (NN example)) (PP (IN of) (NP (JJ asexual) (NN reproduction)))))))))))) (. .)))
Trees send out rootlike extensions that produce new stems is an example of asexual reproduction.