Prairie Fringed Orchis, 19 Prairie June-grass, 6 Prairie Parsnip, 81 Prenanthes, 116 Prickly Ash, 65 Prickly Pear, 77 Primrose, 87 Primrose Family, 87 Primula, 87 Primulaceae, 87 Prince's Feather, 27 Prince's Pine, 85 Proserpinaca, 79 Prunella, 97 Prunus, 54 Psedera, 71 Ptelea, 65 Pterospora, 84 Puccoon, 94 Pulse Family, 58 Purple Avens, 57 Purple Coneflower, 131 Purple Fringed Orchis, 19 Purslane, 34 Purslane Family, 34 Purslane, Water, 78 Putty Root, 16 Pyenanthemum, 98 Pyrola, 84, 85 Pyrus, 52, 54, 55 Quack Grass, 6 Quaking Aspen, 19 Quassia Family, 65 Queen of the Prairie, 57 Quercus, 22, 23 Radicula, 43, 45, 46 Radish, 45 Radish, Horse, 46 Radish, Wild, 44, 45 Ragged Fringed Orchis, 19 Ragweed, 114 Ragwort, 127, 128 Ram's Head Lady's Slipper, 18 Ranunculaceae, 35 Ranunculus, 35-38 Raphanus, 44, 45 Raspberry, 53, 54 Rattlebox, 59 Rattlesnake Master, 80 Rattlesnake Plantain, 17 Rattlesnake Root, 116 Red Ash, 88 Redbud, 58 Red Cedar, 1 Red Clover, 61 Red Currant, 50 Red Maple, 70 Red Mulberry, 24 Red Oak, 23 Red Raspberry, 53 Red-root, 71 Red Sorrel, 25 Red-top, 6 Reed, 6 Reed Grass, 5 Rein Orchis, 18 Reseda, 48 Resedaceae, 48 Rhamnaceae, 71 Rhamnus, 71 Rhexia, 77 Rhus, 68, 69 Ribes, 49, 50 River Weed, 48 River Weed Family, 48 Robinia, 58 Rock Cress, 46, 47 Rocket, Sea, 45 Rock-rose Family, 74 Rosa, 52 Rosaceae, 51 Rose, 52 Rose Family, 51 Rose Mallow, 72 Rose Pink, 89 Rosin Weed, 123 Round-leaved Orchis, 17 Round-leaved Violet, 75 Rowan Tree, 52 Rubiaceae, 108 Rubus, 53, 54 Rudbeckia, 128 Rue Anemone, 39 Rue Family, 65 Ruellia, 107 Rumex, 25, 26 Rush, 10 Rush Family, 10 Rush, Twig, 8 Russian Thistle, 28 Rutabaga, 43 Rutaceae, 65 Sabbatia, 89 Sagina, 32 Sagittaria, 3 Salicaceae, 19 Salix, 20 Salmonberry, 54 Salsify, 115 Salsola, 28 Sambucus, 109 Samolus, 87 Sandalwood Family, 24 Sand Bur, 5 Sand Cherry, 54 Sand Rocket, 42, 43 Sand Spurrey, 32 Sand Violet, 76 Sanguinaria, 41 Sanguisorba, 57 Sanicula, 82 Santalaceae, 24 Sapindaceae, 70 Saponaria, 34 Sarracenia, 48 Sarraceniaceae, 48 Sarsaparilla, 80 Sarsaparilla Family, 80 Sassafras, 41 Satureja, 97 Saururus, 19 Saxifraga, 50 Saxifragaceae, 49 Saxifrage, 50 Saxifrage Family, 49 Saxifrage, Golden, 50 Scarlet Oak, 23 Scheuchzeria, 3 Schneck's Oak, 23 Scirpus, 7 Scleranthus, 31 Scorpion Grass, 94 Scrophularia, 103 Scrophulariaceae, 101 Scrub Oak, 23 Scutellaria, 96 Sea Rocket, 45 Sea-side Crowfoot, 36 Sedge, 8 Sedge Family, 7 Sedum, 48, 49 Self-heal, 97 Seneca Snakeroot, 66 Senecio, 127, 128 Senna, Wild, 60 Setaria, 4 Shag-bark Hickory, 21 Sheep-berry, 111 Sheep Laurel, 85 Shepherdia, 77 Shepherd's Purse, 46 Shingle Oak, 22 Shin-leaf, 84, 85 Shooting Star, 87 Showy Lady's Slipper, 18 Showy Orchis, 17 Sicyos, 112 Sida, 72, 73 Silene, 33, 34 Silphium, 122, 123, 127 Silver Maple, 70 Silver Weed, 55 Silvery Cinquefoil, 66