These are terrestrial bromeliads that are often confused with Agaves thanks to their barbed rosettes and ability to withstand drought so well (most bromeliads are not exactly drought tolerant, but these terrestrials, along with Puyas and Deuterocohnias, are quite well adapted to desert life, and usually planted in the cactus and succulent sections of botanical gardens that can support such species).
Unknown Dyckia species in my yard
Unknown Hechtia (could be H. montana) in private garden
Dyckias are South American plants while Hechtias are primarily from Mexico (some from other Central American countries). These two genera can be difficult to tell apart as both look like non-succulent Agaves (Hechtias are known as False Agaves) having rosettes of arching stiff leaves with incredibly sharp spines/barbs along the leaf margins. Both are suckering plants and prefer full sun and somewhat arid climates. However Hechtias nearly always have white flowers while Dyckia flowers come in a variety of brilliant orange and yellow colors. Dyckias are NOT monocarpic (they keep on growing year after year) but Hechtias die after flowering. Dyckias are one of the most cold tolerant of all the bromeliads (tolerating temps down into the low 20sF and even below in some cases) while Hechtias are one of the least cold tolerant of the terrestrial bromeliads, rarely tolerating more than brief frosts down into the mid 20s.
Dyckia colonies (two different species) showing blooms (typical orange color) and a yellow flower from another Dyckia
Hechtia galeottii flowering and closer up of its whitish flowers; Hechtia podantha in flower (also whitish)
Unlike the Puyas discussed in a previous article, these bromeliad species are grown primarily for their rosettes (many ornamental cultivar exist) and not their flowers. Hechtias in particular have fairly non-ornamental flowers, though a few exceptions exist. Bromeliad flowers, though quite colorful, are still somewhat less than spectacular individually. But large colonies of blooming Dyckias can be quite an arresting sight.
Dyckia 'Brittle Star' (show plant) Hechtia gayii 'Burgundy' Both plants have attractive rosettes
Both do well in garden situations though they also excel as potted plants. These are two of the most difficult and dangerous of all the bromeliad species to prune thanks the unbelievably vicious spines. But the deadly looking leaves can make amazingly ornamental displays as they form radiating symmetrical patterns.
Dyckias and Hechtias are not true succulent plants (though some Dyckias do have fairly thick leaves that must have some succulent properties) but both are fairly drought tolerant. Some Hechtias are far more drought tolerant than many of the common succulents known for their ability to withstand lack of water. However both appreciate regular watering (particularly the Dyckias) in the warmer months of the year. I have rotted a few Hechtias from overhead watering in cooler months, but so far have yet to do the same to any Dyckia species. Neither seem to need much in the way of fertilization, though Hechtias actually seem to do better without added fertilizer, than with some. Both genera have fairly large root systems so if kept in pots, it is better to put them in a larger pot, than in a small one as one would put most potted cacti or succulents in. Overpotting is rarely a problem with these plants, and just results in larger plants more quickly. Cactus soils are OK, but many growers actually recommend soils that are a bit more water retentive (like normal potting soil).
Hechtia marnier-lapostolleis growing in succulent garden in Huntington Gardens get little water except in winter; Dyckia I had planted in full sun in an extreme drought situation obviously overstressed it... some Dyckias are not as drought tolerant as others.
The following are some of the more commonly grown Dyckia species, at least from what I have experienced here in Southern California.
my own Dyckia brevifolia Dyckia encholoririoides x brevifolia in the Huntington Dyckia brevifolia 'Golden Glow'
Dyckia forsteriana Dyckia neiderlenii Dyckia platyphylla
Dyckia pseudococcinea Dyckia rariflora Dyckia remotiflora (one of the 'user-friendly species)
One of the most popular species: Dyckia marnier-lapostollei Dyckia dawsonii
Dyckia macedoi Dyckia maritima Dyckia velascana
Dyckia choristaminea, a dwarf species, makes both a great potted plant but a decent garden plant if you have a small, clear spot for it
There are dozens of Dyckia hybrids, though some are so similar I cannot tell them apart.
Dyckia 'Amythest' Dyckia 'Arizona' Dyckia 'Merlin'
Dyckia 'Keswick' Dyckia 'Silvermoon' Dyckia 'Silver Star'
This is a hybrid of Dyckia forsteriana and a fantastic landscape plant... these shots are from some colonies in the Huntington Gardens, California
Though none are really common in cultivation, the following are some of the more commonly displayed and collected Hechtias in cultivation.
Hechtia conzattiana Hechtia gayii Hechtia marnier-lapostollei
Hechtia glauca is one of the most popular and ornamental species, but a tough grow for me (I tend to rot it, or freeze it to death)
Hechtia montana Hechtia stenopetala unknown but beautiful Hechtia in Huntington Gardens
An unusual species, Hechtia rosea, at least in terms of flower color- bright red