1) Divided into two parts 
arranged in two opposite rows (and hence in the same plane).
two-ranked, arranged in two diametrically opposite rows
leaves or flowers borne in to opposite ranks
in or having two rows
• (n.) Disposed in two vertical rows; two-ranked.
In two ranks; usually applied to the arrangement of leaves or flowers.
two-ranked, that is with leaves on opposute sides of a stem and in the same plane
<plant biology> Arranged in two rows on opposite sides of a stem and thus in the same plane. ... (11 Jan 1998) ... 
In two opposite rows.
leaves or flowers borne in to opposite ranks
distichous 1. A reference to leaves that grow in vertical rows on opposite sides of a stem. 2. Divided into two parts or two rows.
arranged in two rows or ranks
arranged alternately in two vertical rows on opposite sides of an axis, as leaves. · divided into two parts.