New:
Fern
Modeling the Mighty Maple for Web

Gallery of trees

Procedural toy flowers. Bezier spline patches are used. Hand made ~30kb script for the whole garden (in public domain).

fern	strips	twig
foggy garden	umbrella	"electric"
apple tree	roses	hedge
violet	daisy	bush
tulip	flower	grass
asters	"bell"	palm

Let us make more WebGL flowers (have you comments or suggestions?)
How to make procedural plants tutorial draft.
Procedural trees, venation (more textures, see venation dirty draft), realistic lighting (normals...), spline patch editor (or Blender)...

Evgeny Demidov "demidov at ipm.sci-nnov.ru"

Daniel Brown's artworks. More images at Darwin - Daniel Brown for the D'Arcy Thompson Zoology Museum
Wild Flower from resn.co.nz
Time-Lapse Notes on Growing Plants by Ted Kinsman
Structures that unfold like flowers by Jessica
Lighting 3D trees by Ocean Quigley
Vegetation improvements and More trees and texture tricks by mtnphil