CACTI

The shoe fits when it comes to collective nouns. Consider a flock of predictable sheep or a murder of watchful crows. Owls are solitary birds but when they come together they do so in parliament, perching no doubt in the upper house, their peers donned in crimson robes and horse hair wigs. While an army of caterpillars conjures a bright fuzzy image with thousands of paired feet on the move, chubby legged alligators congregate and pigs drift.

In the plant kingdom, the family Cactaceae is split into three collectives known as tribes. Each share a kinship for sun worship, independent living against the odds and an impressive capacity for water retention, but vary madly in looks from clan to clan. The totem of all cacti, that which populates the landscape of Speedy Gonzales cartoons and springs to mind when you think cactus', belongs to Tribe Cereeae and bears no resemblance whatsoever to flowering Peireskieae. The plant found on the Mexican flag is called the prickly pear cactus, the Opuntieae tribe's mascot which also happens to be edible.

Last year I spent some time on a smallholding on the northeastern fringes of Mexico City. Dry white clay that marks the Atizapan region also happens to be particularly hospitable for prickly pear cactus (or nopal). Sometimes used as fencing (the cactus curtain' in Cuba prevented escape to the US) nopales are more often served sandwiched between tacos or scattered loose in salad. It was the promise of huevos con nopales for breakfast that set me along a rocky hillside in my pyjamas one morning, dutifully following five members of the Bonilla family, who owned a small field full of nopales plants. They had convinced me that harvesting nopales would be fun and rewarding. Having tried tinned nopales once before (bland slimy shoots mixed with corn) I can't say I relished the idea, but with very poor Spanish all I could do was nod enthusiastically, politeness pushing me along a rocky ravine in pursuit of the prickly pear.

In slippered feet I gained foothold onto a field lined with Mexican cypress where hundreds of nopal trees were huddled together in long curving rows. We tread carefully past a pack of mean looking watch dogs, snoozing soundly in the shadow of cacti over 10 feet tall. Prickly pear cacti have large, flat pincushion pads that sprout baby pads which look like mini mouse hats. Juicy baby buds curiously known as tuna' are cut easily from the adult bud and stuffed inside older pads, then grilled on the BBQ.

It was lunchtime by the time we returned home. My harvest was declawed of their espinas', boiled with salt and an onion bulb, then served in the most common and delicious way long thin slices cut and tossed with chilli, fresh tomato, onion, coriander and a generous squeeze of lime served in what is collectively known as Ensalada de Nopalitos.

Kate O'Brien is the editor of The Plant.

Pictured: a cyanotype of Opuntia (prickly pear), created for Toast Travels by Holly Mitchell.