P. madagascariense is a small
perennial shrub growing tall. The branches are hairless and quadrangular. The fleshy leaves are
sessile, borne
opposite one another, measuring by with finely toothed margins. The
inflorescence is a
terminal corymbose cyme bearing three to ten flowers. The flowers measure approximately across and are
hexamerous or, rarely, pentamerous. The
petals are white with a red to orange tint and purple veins. ==Conservation status==