University of Toronto – St. George Faculty of Arts & Science
Desert House
Xerophytes are plants that are adapted for arid environments. Common xerophytic features include: succulent tissues that store water and organic acids, photosynthetic stems with reduced surface area, waxy cuticles to limit water loss, sharp spines, reflective hairs, and underground tubers. Xerophytism is an example of evolutionary convergence, in which distinctly dissimilar ancestors give rise to similar descendants through selection for a common set of features.
CACTUS FAMILY (Cactaceae, stem succulents. North, Central and South America)
With one exception, cacti inhabit only the Americas. They are highly adapted to growing in desert environments. Cacti are fleshy stems with spines (highly modified leaves) that offer protection against herbivores.
Bruce Hall
Chief Horticulturist Emeritus
Retired 2017.
Blue myrtle columnar cactus [Myrtillocactus geometrizans]
Bishop’s Cap Cactus [Astrophytum myriostigma]
Astrophytum myroistigma
Old man cactus [Cephalocereus senilis]
Cylindropuntia ramosissima ‘cristata’
Notocactus schlosseri
Christmas cactus [Schlumbergera truncata]
Golden barrel cactus Echinocactus grusonii
SUCCULENT FAMILY
(Crassulaceae, worldwide distribution, many CAM species)
The family has no important agricultural crops, but several taxa are grown horticulturally and used in rock gardens.
SPURGE FAMILY (Euphorbiaceae, worldwide distribution)
Poisonous diterpene esters and lectins are widely present in the family. The milky latex released by plants can blister skin, blind eyes, and can cause vomiting if ingested. Also an important source of natural rubber and oil.
Candelabra tree [Euphorbia candelabrum]
Crown of thorns [Euphorbia milii]
Baseball “cactus”[Euphorbia obesa]
Euphorbia obesa inflorescence.
Euphorbia caput-medusae
Euphorbia tetragona
Euphorbia buruana</i?
Candle Plant [Euphorbia unispina]
ICE PLANT FAMILY (Aizoaceae. Mostly native to Africa.)
Succulent leaves with bladder-like cells in the epidermis is characteristic of the family.
Mesembryanthemum crystallinum
Ice plant [Mesembryanthemum salmii]
Pleiospilos nelii
Pleiospilos nelii
Living stones [Lithops hallii]
Tiger Jaws [Faucaria felina]
Corpuscularia lehmannii
ASPHODELACEAE FAMILY
Family includes succulent ornamental genera Aloe, Gasteria and Haworthia.
Aloe ferox
Aloe ferox
Aloe arborescens
Aloe melanacantha
Aloe brevifolia
Aloe rauhii ‘Doran Black’ hybrid
Aloe humilis
Haworthia cuspidata
Haworthia cuspidata
Haworthia reinwardtii
Haworthia cymbiformis
Klein Karoo Gasteria [Gasteria brachyphylla]
Gasteria brachyphylla inflorescence
Gasteria bicolor var. lilliputana
Ox-tongue plant [Gasteria obtusa]
Lace Aloe [Aristaloe aristata]
DOGBANE FAMILY (Apocynaceae including subfamilies Asclepiadoideae, Rauvolfioideae)
Worldwide distribution. Some taxa such as Carrion flowers [Stapelia] emit the scent of rotting flesh to attract pollinators, while others like Frangipani [Plumeria] emit a sweet aroma to attract moths.
Frangipani [Plumeria rubra]
String of hearts [Ceropegia woodii]
Ceropegia woodii
Ceropegia radicans
Red Dragon Flower [Huernia schneideriana]
Stapelia angulata
Stapelia hirsuta
Stapelia hirsuta
Stapelia gigantea
Stapelia bella
Sansevieria thyrsiflora
Stapelia comparabius
Blow flies on Stapelia hirsuta
Madagascar palm [Pachypodium lamerei]
Madagascar palm [Pachypodium lamerei]
ASTER FAMILY (Asteraceae)
String of pearls [Senecio rowleyanus]
Pencil ragwort [Senecio anteuphorbia]
Hotdog plant [Senecio articulatus]
WELWITSCHIACEAE FAMILY
(Monospecific gymnosperms)
Welwitchia mirabilis
Welwitchia mirabilis cones
OTHER FAMILIES (Asparagaceae, Zamiaceae, Acanthaceae)