Giant fennel 
Giant hogweed 
Giant Tangier Fennel 
Golden alexanders 
Goutweed 
Great Basin Desert Parsley 
Great masterwort 
Great Masterwort 
Hacquetia epipactis 
Hairy Angelica 
Harbinger of Spring 
Heart-leaf Alexander 
Hemlock Water-Dropwort 
Hemlock waterparsnip 
Heptaptera anisoptera 
Heracleum humile 
Indian biscuitroot 
Johrenia dichotoma 
Kippernut 
Knotted Hedgeparsley 
Laserwort 
Leavenworth's Eryngo 
Lecokia cretica 
Lesser flannel flower