| Are Pineapples Succulents?
In so many words, no they're not. But in order to extend this month's column beyond seven words, I'm going to discuss a number of other members of the bromeliad family that approach the ill-defined boundaries of what is and what isn't a succulent plant. Though no bromeliads have truly developed the extreme modifications that enable typical succulents to thrive in their arid environments, nonetheless several genera within the Bromeliaceae have successfully colonized the deserts and semi-arid landscapes of North and South America to the point where they constitute a significant portion of these habitat's perennial, xerophytic flora. Moreover, most bromeliad growers ignore these plants, while a few examples will crop up in many collections of succulents and cacti.
The bromeliad family consists of three sub-families or tribes. Plants within the Bromelioideae generally grow as epiphytes, have more-or-less spiny leaves and berry-like fruits. These include familiar "living vase" plants such as Aechmea and Neoregelia. Members of the Tillandsioideae, again, generally epiphytic, have spineless leaves and tiny, wind-distributed seeds. The silvery plants of Tillandsia, and Vriesea, with its open vase forms, are the most familiar members of this tribe. The last tribe, the Pitcairnioideae, less common in cultivation, are almost all terrestrial plants, with tubular flowers and dry fruits.
Even though most members of the first two tribes live in humid tropical forests, up in the trees along with orchids, several genera and species have made themselves at home on the ground. Among the Bromelioideae, Bromelia and Ananas (that's the genus of the pineapples) live terrestrially, making medium to large size rosettes of stiff leaves with spiny edges. Bromelia often serve as living fences, armed fiercely enough to keep out hungry wandering cattle and other livestock. But, though somewhat drought resistant, these plants don't grow in really dry regions, and their leaves show only rudimentary modifications for life without water.
The great majority of species within the Tillandsioideae live in rain and cloud forests, as far removed from desert climates as imaginable, but a few odd Tillandsia species have managed to adapt to life in one of the driest places on Earth, the coastal deserts of Peru, where it may literally never rain in some areas. Tillandsias absorb moisture through their leaf surfaces, which are covered with little cells that resemble open-mouthed jugs. Among tillandsias, the denser the silvery scurf on their surfaces, or the fuzzier and more plumose the leaves, the drier the environments in which the plants live. Anyone who's ever seen tillandsias growing happily on telephone wires in Central or South American cities must realize that these plants can get by with very little, but Peruvian species such as Tillandsiapurpurea thrive on coastal sand dunes, absorbing water from the fogs in places where not even cactus can survive. These plants are true xerophytes, but they've evolved a way of coping with dry climates quite different from those used by plants we think of as succulents.
It's many of the species found in the third tribe, the Pitcairnioideae, that most approximate the succulent life style. The namesake genus of the group, Pitcairnia, generally grows under moist conditions, but several of the other genera range throughout New World deserts, from Texas all the way down to Chile. Hechtia, with a single species in Texas (Hechtia scariosa, formerly know as H. texensis), grows all over the dry parts of Mexico, frequently in conjunction with some of the rarest and most arid growing cacti. Hechtia form rosettes of somewhat thickened, often extremely spiny leaves. They vaguely resemble agaves (H. scariosa is sometimes called "false agave"), but their leaves are proportionately narrower, and more-or-less densely covered with a whitish or silvery scurf that can turn red in bright sunlight. The rosettes flower repeatedly (unlike agaves), but their tubular, whitish flowers aren't particularly striking. Hechtiaglomerata, widely distributed throughout Mexico, resembles a larger H. scariosa, with two- or three-foot rosettes composed of many long, narrow, spiny leaves, either silvery-white or reddish in color. H. argentea, and (even more so) the highly endemic H. marnier-lapostollei, combine dramatically large spines with intense silver coloring. In contrast, H. coerulea (formerly called Niveophyllum coeruleum), from extremely arid hillsides, has flattened, thick, pale green leaves with barely visible spines, and produces a spray of dozens of tiny, pale purple flowers that nod in the faintest breeze.
Dyckia , centered in Brazil but extending into neighboring countries and as far west as Chile, more-or-less resembles Hechtia, but its flowers generally are brightly colored in hues of yellow, orange or red. Some dyckias grow along rocky outcroppings in areas otherwise dominated by seasonally dry tropical forests, while others live in genuinely arid places. The usually many-leafed rosettes range from less than six inches across to a couple of feet in diameter, and most species ultimately form dense clumps. Dyckia rariflora, small and with relatively few spines, keeps its rosettes close to the ground. D. leptostachya, larger and with fewer leaves, looks more like a Hechtia, while D. fosteriana, with small, silvery, almost metallic-looking rosettes made of many narrow, spiraling leaves, immediately appeals even to people who don't ordinarily like spiny things. Dyckia marnier-lapostollei (not be confused with the hechtia of the same name) may be the most coveted species; its very thick, bright silver leaves have a soft, almost velvety texture and are densely fringed with tiny, relatively innocuous spines. Dyckia odorata, almost unknown in cultivation, makes dense-leafed rosettes only five or six inches across, delicate looking, but armed with small but effective spines.
The most famous terrestrial bromeliads are a few members of the large, mostly Andean genus Puya. These plants, which along with dyckias take the place of the mostly North American agaves and yuccas, grow in some of the harshest conditions on the planet, sometimes in high altitude deserts with an average daily temperature range of 100 degrees Fahrenheit, sometimes in high altitude peat swamps that freeze every night of the year, sometimes in the almost rainless coastal deserts of Chile. Puyas range from fairly small plants, such as the Peruvian P. laxa, growing on rocks near the ruins of Machu Picchu, to enormous species such as P. raimondii, with a ten foot rosette and a thirty-five foot tall flower spike. Other species form branching trunks and resemble Joshua trees. Many puyas have remarkable inflorescences. Among these is P.alpestris, with thirty inch, nastily spiny rosettes and a three-foot tall, branching, densely blossomed flower spike. Its tubular flowers are silky textured and unearthly turquoise blue in color, with an upright stalk of bright orange anthers topped with a clump of chartreuse-green stigmas. The flowers are filled with deep purple colored nectar that both smells and tastes just like the artificial butter used in movie-house popcorn. Very similar, but with larger rosettes and metallic green rather than turquoise flowers, P.berteroniana, rarer than P.alpestris in cultivation, is regarded as even more spectacular when in flower. When cultivated plants of these species flower, pictures of them frequently show up in the local news media, whether in the Bay Area or in Europe. With smaller rosettes and less vicious spines, P. nana puts out a low dome-shaped inflorescence, bright pink with tubular purple flowers poking out.
Last, and least (in size anyway), the relatively few species of Abromeitiella, from Argentina and Bolivia, grow into dense mounds of spiny rosettes ranging from a couple of inches in diameter to less than half an inch. A. chlorantha, one of the larger species, has surprisingly dagger-like, stiff little leaves and tubular green flowers. A. brevifolia, so small that its clumps resemble mounds of moss, comes with rosettes made of short, somewhat flexible but still sharp-tipped leaves and similarly green, stemless blossoms. Given time these plants will grow into rounded, sculptural mounds, filling the crevices in which they live, or mimicking small green boulders.
There are several other, infrequently encountered genera of these plants; some, such as Deuterocohnia and Encholirium, grow in arid surroundings, while the others often live in exposed, chilly and windswept rather than desert-like environments. All the ones discussed are quite easy to grow, thriving in full sun and any fast draining soil mix. Though drought tolerant, they will all survive outdoors despite our winter rains. In containers they should be watered every week or so in the warm months, from once every two weeks to half that often in winter depending on where they originate. The smaller ones make very decorative, though sharp-edged, container plants, whether in a sunny window or outdoors. Most will also do very well in a succulent or rock garden. Some puyas can be very aggressive, and if growing them in the ground, make sure they have plenty of room to spread. Transplanting or dividing clumps of these plants is never fun. Still, they make distinctive, attractive, hardy candidates for outdoor growing.
The Garden has an excellent collection of these plants, with many large specimens growing outdoors and a number of smaller ones in the greenhouses. We always have some of these available at sales, just be sure to ask how big they'll get.
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