According to botanist estimates, the unique ecosystems of the Baja Peninsula and its islands support more than 4,000 varieties of plants. For an introduction to about 550 of them, consult the Baja California Plant Field Guide, by Norman C. Roberts. Here are some of the highlights:
Scientists have identified 120 species of cactus here, and the majority of them live only on this peninsula or its offshore islands. Many of them flower after summer and fall rains, painting the desert in splashes of bright color for a few weeks of the year. One of the most common cacti in Baja is the cardón (Pachycereus pringlei), the tallest of them all, which is especially prevalent in the Valle de los Gigantes  (Valley of the Giants) south of San Felipe. They can grow to heights of 18 meters (60 ft.) and weights of 12 tons (not counting the roots), and they live for hundreds of years.
Less common but also unique to Baja, the biznaga (Ferocactus), or barrel cactus, lives only on a few islands in the Sea of Cortez. It has red-tinged spines and blooms yellow and red flowers in the spring.
The indigenous Pericú treasured the pitahaya dulce, or organ pipe cactus, for its watermelon-like fruit. During the late summer and early fall harvest, the Pericú ate the abundant fruit until they fell asleep, waking only when they were ready to eat some more. The species lives south of the Sierra de San Borja  in Central Baja and on a few islands in the Sea of Cortez. A related species, pitahaya agria (galloping cactus) has a less sweet but still edible fruit.
Multiple kinds of cholla and nopal (prickly pear), both part of the Opuntia species, grow throughout the region. The nopal is an edible cactus, common on menus up and down the peninsula.
Nineteen types of agave are found in Baja, including several varieties of yucca. Agaves are pollinated most commonly by bats and flower only after several years. Many of them are edible. The tree yucca, or datilillo (little date), looks a lot like a date palm and thrives on the west side of the Vizcaíno Desert , among other places. You can eat its fruit and flowers, boil its roots to soften soap or leather, and weave the leaves into sandals, baskets, or mats. Maguey, or century plant, flowers only once in its lifetime, sending up a tall, slender stalk after maturation. It was another major source of food and fiber for the indigenous people that inhabited the peninsula.
The most striking plant in this family of succulents is easily the most distinctive in all of Baja. Indeed, the tall and lanky cirio (candle) or Boojum tree looks like an upside-down carrot—something right out of a Dr. Seuss book. Almost as tall as the cardón, it grows about three centimeters a year and lives for hundreds of years. In order to see this unusual plant, you have to venture into central Baja. It only grows between the southern end of the Sierra de San Pedro Mártir  and the Sierra Tres Vírgenes  and on Isla Angel de la Guarda, near Bahía de los Angeles . If you’re driving the Transpeninsular Highway south, your first glimpse of the species comes as you enter the desert below El Rosario .
Also part of the same family, the ocotillo and palo adán (Adam’s tree) are found throughout the peninsula and often used to make fences.
A universal symbol of the tropics around the globe, palm trees are used as landscaping in warm climates all over North America. But there is something spectacular about seeing them grow in the wild, especially when they are clinging to the walls of a deep canyon high in the sierras. Seven varieties live in the Baja California wilderness. Besides providing shade and an overall tropical aesthetic, they are used to make woven baskets, thatched roofs, and construction materials such as roof beams or rails for fences.
The endemic blue fan palm (also called the Mexican blue palm, and in Spanish palma ceniza or palma azul) has bluish-colored leaves and grows from the canyons and arroyos of the Sierra de Juárez  in the north to San Ignacio  in the south, reaching heights of 24 meters (79 ft.).
The smallest palm found in Baja is the tlaco palm (also called the palma palmia and the palma colorado). It’s found south of Loreto. The tallest palm in Baja, also with fan-shaped leaves, is the Mexican fan palm (Baja California fan palm, skyduster, or palma blanca). It tops out at 27–30 meters (90–100 ft.).
Spanish Jesuit missionaries brought the feather-leaf date palm to Baja, and it continues to thrive near Loreto , Comondú , Mulegé , San Ignacio , and San José del Cabo . And the coconut palm (cocotera), the only other feather-leaf palm in Baja, grows south of Mulegé.
Part of the sumac family of trees that emit a milky sap, the Pachycormus discolor (copalquín or torote blanco in Spanish) has a gnarled trunk and branches covered in a gray-white outer layer that peels off, exposing a smooth blue-green inner bark. It’s most common in the Desierto Central. This tree is often confused with Bursera odorata (pachycormus, also called torote blanco in Spanish), a member of the torchwood family, which has a yellow inner bark and grows south of Bahía Concepción .
An unexpected delight when exploring the interior of the peninsula is the wide variety of conifers that grow in the high sierras. Cypress, cedar, juniper, white fir, and lodgepole pine are just a few examples. The Tecate cypress grows on the western slopes of the Sierra de Juárez  and north to Orange County in Alta California, while the San Pedro Mártir cypress lives on the eastern escarpment of the Sierra de San Pedro Mártir . Cedros Island  in the Pacific Ocean has its own endemic conifer, the Cedros Island pine, as does Isla Guadalupe, with the Guadalupe Island pine.
If you browse any of Baja’s arts and crafts markets, you’ll often see shelves filled with animals carved out of wood. The raw material for these crafts comes from the ironwood tree (palo fierro or tesota in Spanish). A hard, hot-burning wood, it has been logged extensively on the peninsula and is no longer as common as it once was.
Mimosas are a subfamily of the pea family (Leguminosae), all of which have linear seedpods and double rows of tiny leaves. Within this subfamily, mesquite and acacia occur throughout the peninsula. Baja’s indigenous people had many uses for mesquite wood, from construction materials to herbal remedies, and the traditions are carried on today by those who live in the most rural parts of the peninsula.
When it blooms in the spring, the small white blossoms of the palo blanco tree are a sight to behold. The Sierra de la Giganta, near Loreto , is one of the best places to find it.
Even figs grow wild in Baja. Called zalates, they tend to prefer the rocky areas of Southern Baja, below La Paz .
A number of herbs used in cooking and alternative medicine thrive in the hot, dry Baja climate. For example, white sage is found on the rocky hillsides in Northern Baja. Another type of sage, the rare chia, grows only in the desert areas of Baja, Sonora, and the southwestern United States. But the herb most commonly associated with Baja California is damiana (Turnera diffusa), consumed either as a tea or in a liqueur and believed to be a powerful aphrodisiac. When you see a Baja margarita on the menu, it usually contains damiana liqueur instead of triple sec. This shrub prefers the rocky areas of Southern Baja, near the capes.