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Cactus Cacti are a group of plants native to North, South, and Central America that have evolved water conserving morphology that allows them to survive in dry environments. Back to plant growth form menu Next Back to vegetative parts main menu Main menu Cactus The major adaptation to dry conditions is reduction or loss of leaves that are replaced by sharp spines. In addition, the stem becomes swollen to retain moisture and is the major photosynthetic organ. Back to plant growth form menu Back Next Back to vegetative parts main menu Main menu Cactus Pereskia is an exception to the general cactus morphology producing true leaves as its photosynthetic organ. Pereskia grandiflora Pereskia aculeata Back to plant growth form menu Back Next Pereskia lychnidiflora Back to vegetative parts main menu Main menu Cactus In addition to spines, cacti produce a number of unique morphological features including tubercles, areoles and cephalium. Back to plant growth form menu Back Next Back to vegetative parts main menu Main menu Cactus Tubercle Spine Tubercle Tubercle is the general term for a raised area or protuberance on the surface of a plant. In cactus, it is a raised area formed by the fusion of the stem and modified leaf petiole (technically called the Podarium). Areole The apical portion of the tubercle is often occupied by the areole that contains modified leaves in the form of multiple spines. Weingartia Back to plant growth form menu Back Next Back to vegetative parts main menu Main menu Cactus Ribs In some cases, the tubercles merge to form vertical ridges or ribs. Astrophytum ornatum Uebelmannia pectinifera Back to plant growth form menu Back Next Back to vegetative parts main menu Main menu Cactus Areole An areole is a meristematic area where the spines and in some cases flower buds are formed. Areole Areole Back to plant growth form menu Back Next Areole Back to vegetative parts main menu Main menu Cactus Cephalium Cephalium is a woolly and bristly area at the top or on one side of some cactus species where flower buds are formed. Pachycereus pectinarboriginum Back to plant growth form menu Back Next Back to vegetative parts main menu Main menu Cactus Cephalium In Melocactus, there is a distinct change in the plants appearance as it progress from the juvenile to mature phase. Mature phase The mature phase growth is represented by apical cephalium tissue and has the ability to flower. Juvenile phase Back to plant growth form menu Back Next Back to vegetative parts main menu Main menu Cactus Cephalium When the cephalium occurs on the side of the stem, it is referred to as lateral cephalium or pseudocephalium. Cephalocereus maxonii Back to plant growth form menu Back Next Back to vegetative parts main menu Main menu Cactus Cactus flowers are often large and colorful. Echinopsis Astrophytum Rebutia Back to plant growth form menu Echinocactus Back Next Back to vegetative parts main menu Main menu Cactus Flowers Flowers are characterized as having many stamens and petals with an inferior ovary and sometimes an elongated floral tube. Echinopsis Ovary Floral tube Styles Stigma Stamens Petals Ovules Longitudinal section of a cactus flower. Back to plant growth form menu Back Next Back to vegetative parts main menu Main menu Cactus Fruit Cactus fruit are berries. Mammillaria Back to plant growth form menu Cereus Back Next Back to vegetative parts main menu Main menu Cactus Fruit In some cacti, the fruits are edible. Prickly pear cactus (Opuntia) Back to plant growth form menu Back Next Dragon fruit (Hylocereus) Back to vegetative parts main menu Main menu Cactus Cactus shapes Cacti take on several general shapes that include: Columnar ceroid Reclining ceroid Branched ceroid Trailing ceroid Globular - cylindrical Globular - spherical Segmented - upright Segmented – trailing Epiphytic Climbing Back to plant growth form menu Back Next Back to vegetative parts main menu Main menu Cactus Columnar ceroid Columnar ceroid cacti have upright growth and a similar diameter from base to tip. Pachycereus marginatus Cleistocactus Back to plant growth form menu Back Next Back to vegetative parts main menu Main menu Cactus Reclining ceroid Reclining ceroid cacti grow parallel to the ground. Stenocereus eruca Back to plant growth form menu Back Next Back to vegetative parts main menu Main menu Cactus Branched ceroid Branched ceroid cacti are upright with several branches. Cereus peruvianus Carnegiea gigantea Back to plant growth form menu Back Next Back to vegetative parts main menu Main menu Cactus Trailing ceroid Trailing ceroid cactus have a trailing or hanging growth. Bolivicereus Hylocereus udatus Back to plant growth form menu Back Next Back to vegetative parts main menu Main menu Cactus Globular - cylindric Globular – cylindric cacti have a short stature and are a barrel-like shape. Ferocactus echidne Astrophytum Back to plant growth form menu Back Next Back to vegetative parts main menu Main menu Cactus Globular - spherical Globular – spherical cacti are short with rounded growth. Mammillaria geminispina Notocactus magnifica Back to plant growth form menu Back Next Back to vegetative parts main menu Main menu Cactus Segmented - upright Segmented – upright cacti can have segments with flat stems (phyllocades). Opuntia Back to plant growth form menu Back Next Back to vegetative parts main menu Main menu Cactus Segmented - upright Other segmented – upright cacti have segments with rounded stems. Cylindropuntia Back to plant growth form menu Back Cylindropuntia imbricata Next Back to vegetative parts main menu Main menu Cactus Segmented - upright Jumping cholla (Cylindropuntia bigelovii ) stem segments readily fall from the plant and are moved around as propagules. Pack rat burrow A desert pack rat will collect cholla stems to line its burrow. Back to plant growth form menu Back Next Back to vegetative parts main menu Main menu Cactus Segmented - epiphytic Segmented – epiphytic cacti usually have phylloclade stems and hang. Schlumbergera Back to plant growth form menu Rhipsalidopsis Back Next Back to vegetative parts main menu Main menu Cactus Segmented - epiphytic Epiphytic – trailing cacti that grow in tree-tops in subtropical environments. Rhipsalis Epiphyllum Back to plant growth form menu Back Next Back to vegetative parts main menu Main menu Cactus Epiphytic - climbing Epiphytic – climbing cacti cling to tree supports and produce adventitious roots. Selenicereus anthonyanus Back to plant growth form menu Back Back to vegetative parts main menu Main menu
