Just found this database by which you can search for plants with certain activities. I've pulled out listings of plants with hypotenisve activities. Its worth a look.
Dr. Duke's
Phytochemical and Ethnobotanical Databases
Plants with the ability to lower blood pressure.
Plants with the greatest number of chemicals
http://www.ars-grin.gov/duke/index.html
Origanum vulgare (Common Turkish Oregano) Plant - 10 chemicals
Berberis vulgaris (Barberry) Plant - 8 chemicals
Catharanthus roseus (Madagascar Periwinkle) Plant - 8 chemicals
Nicotiana tabacum (Tobacco) Leaf - 8 chemicals
Angelica sinensis (Chinese Angelica) Root - 7 chemicals
Arctostaphylos uva-ursi (Bearberry) Leaf - 7 chemicals
Chelidonium majus (Celandine) Plant - 7 chemicals
Coptis chinensis (Chinese Goldthread) Rhizome - 7 chemicals
Coptis japonica (Huang-Lia) Rhizome - 7 chemicals
Coptis spp (Generic Goldthread) Rhizome - 7 chemicals
Corydalis spp (Fumewort) Plant - 7 chemicals
Crataegus laevigata (English Hawthorn) Fruit - 7 chemicals
Erythroxylum coca var. coca (Coca) Leaf - 7 chemicals
Ginkgo biloba (Ginkgo) Seed - 7 chemicals
Hypericum perforatum (Common St. Johnswort) Plant - 7 chemicals
Azadirachta indica (Neem) Leaf - 6 chemicals
Crataegus laevigata (English Hawthorn) Leaf - 6 chemicals
Equisetum arvense (Field Horsetail) Plant - 6 chemicals
Glechoma hederacea (Alehoof) Plant - 6 chemicals
Hydrastis canadensis (Goldenseal) Root - 6 chemicals
Leonurus cardiaca (Motherwort) Plant - 6 chemicals
Or by concentration
Rauvolfia serpentina (Indian Snakeroot) Seed - 1,523,800 ppm total [2 chemical(s)]
Tetrapanax papyrifera (Rice Paper Tree) Pith - 1,014,840 ppm total [3 chemical(s)]
Solanum torvum (Susumba) Fruit - 850,800 ppm total [3 chemical(s)]
Tilia sp. (Basswood) Fruit - 846,000 ppm total [1 chemical(s)]
Robinia pseudoacacia (Black Locust) Leaf - 810,000 ppm total [2 chemical(s)]
Spartium junceum (Genet) Stem - 807,000 ppm total [2 chemical(s)]
Elytrigia repens (Couchgrass) Plant - 711,700 ppm total [3 chemical(s)]
Mimosa pudica (Sensitive Plant) Leaf - 706,740 ppm total [3 chemical(s)]
Cenchrus biflorus (Two-Flowered Sandspur) Shoot - 678,000 ppm total [1 chemical(s)]
Frangula purshiana (Cascara Buckthorn) Bark - 652,780 ppm total [4 chemical(s)]
Sophora secundiflora (Mescal Bean) Seed - 625,800 ppm total [2 chemical(s)]
Juncus effusus (Rush) Leaf - 620,000 ppm total [1 chemical(s)]
Melilotus indica (Small-Flowered Melilot) Plant - 614,800 ppm total [2 chemical(s)]
Tephrosia purpurea (Purple Tephrosia) Leaf - 613,600 ppm total [4 chemical(s)]
Boehmeria nivea (Ramie) Shoot - 610,000 ppm total [2 chemical(s)]
Ricinus communis (Castorbean) Leaf - 601,400 ppm total [6 chemical(s)]
Myrica cerifera (Bayberry) Leaf - 596,000 ppm total [1 chemical(s)]
Artemisia vulgaris (Mugwort) Leaf - 559,650 ppm total [4 chemical(s)]
Anogeissus latifolia (Gum Ghatti) Leaf - 544,600 ppm total [2 chemical(s)]
Equisetum arvense (Field Horsetail) Plant - 542,614 ppm total [6 chemical(s)]
Try it and have a look for yourself. It also has some other interesting links.