Caryophyllaceae (Pink family)

Opposite leaves and a swollen node as on this Dianthus deltoides (Maiden pink).

leaves opposite

swollen nodes

notches in flower petals

superior ovary

5 or 5+5 stamen

fruit capsule

Notched petals and 5 + 5 stamens as in this Arenaria fendleri (Fendler's sandwort),