Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Variation in vein density (VD) with plant phylogeny and growth form. Bars represent standardized values for VD, with outward and inward bars representing values above and below the mean, respectively, and colors representing different growth forms. Branch colors in phylogeny represent main phylogenetic clades. Ma, million years ago.
