Interior photographs © Brian McGowan, except for the following:
© armitageimages.net: 95 bottom; © 2008 Paul Ashford, www.NZplantpics.com: 109 bottom; © Binny Plants: 149 bottom; © Pat Breen, Oregon State University: 110 top; © Scott Calhoun: 123 bottom; ©Rob Cardillo: 42, 61, 62, 109 top, 133 bottom, 147, 176, 180 bottom, 187 top, 193 bottom; © Vicki Demetre, Kruckeberg Botanic Garden: 105 top; © Derek Fell: 99 bottom, 116 bottom, 130 bottom, 137, 150 bottom, 164 top, 173 bottom, 174 top, 179 bottom; © 2008 Garden Picture Library: Friedrich Strauss 88 top, Richard Bloom 170 bottom, Neil Holmes 170 top; © Garden World Images/J. Need: 92 top; © 2004 Horticopia, Inc.: 106 top; © Image Botanica, Inc.: 153 bottom © Mary Sue Ittner: 163 top; © Dency Kane: 87 bottom, 175 bottom, 188 top; © Rosemary Kautzky: 84 bottom, 93 bottom, 94 bottom, 96 bottom, 97 top, 107 bottom, 113 top, 120 bottom, 121 top, 123 top, 124 top, 126 bottom, 142 top, 144 bottom, 188 middle, 194 bottom, 195; © MACORE, Inc.: 34, 96 top, 112 top, 127 bottom, 128, 129 bottom, 135 top, 136 top, 146 top, 155 top, 157 top, 166 top, 171, 186 top, 190 top; © David E. Martin, www.haworthia.com: 134 bottom; © Jerry Pavia: 19 top, 84 top, 91 bottom, 93 top, 94 top, 98 top, 103 bottom, 11, 113 bottom, 114 bottom, 117 top, 130 top, 134 top, 139 top, 141 bottom, 143, 145 bottom, 148 top, 149 top, 150 top, 151 bottom, 156, 158 bottom, 162, 163 bottom, 165, 169 top, 182 top, 188 bottom, 190 bottom, 191, 194 top; © Plant Delights Nursery, Inc.: 119 top; © San Marcos Growers: 144 top; © Steve Silk: 24, 27; © Duncan Smith/Science Photo Library: 103 top, 131 bottom, 138 bottom; © Geoff Stein: 183 top; © Thompson & Morgan Seedsmen, Inc.: 98 bottom, 142 bottom; Mars Vilaubi: 29, 88 bottom, 192 top; © Andy and Sally Wasowski/Lady Bird Johnson Wild Flower Center: 107 top