Desert Flowers 2018 Part 1

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I've been taking photos of some of our desert flowers this spring.

April is time for the yellow legume trees to flower. We have two native species, which used to be called Cercidium floribundum and C. microphyllum. They have been moved into Parkinsonia, the same genus as a Mexican tree widely planted here, Parkinsonia aculeata. All are known as palo verde, which means green stick. They have tiny, rapidly-deciduous leaflets, and most of the year trees photosynthesize with their bark. These are some of the most widespread landscape trees here due to low water use and beautiful growth. I didn't manage to capture vistas of trees in flower, but in April one can see thousands everywhere.

P. aculeata has much brighter and larger flowers, but it is a rank-growing and brittle tree that breaks easily in our monsoon storms. Plus, our two native long-horned beetles prefer it to the native species. As a result, trees usually have weak roots, and blow over easily during storms. Unfortunately, P. aculeata is breeding with the native species, extending far out into the surrounding desert. Hybrids inherit the rapid, weak growth from aculeata. Sometimes hybrids have the smaller and duller flowers from the other two parents, and other times they take after aculeata.

I didn't take photos of mesquite flowers because they're extremely unspectacular.

All these desert legumes were used as food by people here. The dry pods of mesquites are sweet. Dried seeds of these trees look like shiny beans. They store well, and can be cooked like beans.

These photos show two hybrids as landscape trees, and two Cercidium microphyllum on my property.

Cercidium hybrid


Cercidium hybrid


Cercidium microphyllum


Cercidium microphyllum



Botanists have been hard at work changing names in the bean family so they can get their own names appended to the Latin binomials. The bean family Fabaceae was for years divided into three subfamilies based on flower shape: Fabaceae, with typical sweet-pea flowers; Caesalpiniaceae, with much more flat and open flowers, having very long stamens and pistils; and Mimosaceae, including acacias and mesquites, with tiny flowers in clusters. The Cercidiums were in Caesalpiniaceae.

Now Fabaceae is divided up into many other subfamilies. Genus Acacia at one time was used for plants worldwide. The type species was Acacia nilotica in Africa. Now only some of the Australian ones are called Acacia. African Acacias are now in genera Vachellia and Senegalia. This involved botanists moving the type species of genus Acacia to a different genus, and designating a new type species. To me this seems as fundamentally wrong as you can get from the perspective of the Botanical Code. The type species of a genus is supposed to be the defining species for the genus, and all other species put there should be closely related to it. Many botanists saw this strange name change as an offence against African botanists by those in more powerful countries.

The former New World Acacias have been renamed Acaciella and Mariosousa. Everybody I know still calls our local cat's claw tree Acacia greggii. I think mesquites are still legally in genus Prosopis.

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This photo shows a developing Agave tequilana inflorescence.

Agave angustifolia variety tequilana


Yes, this is the famous blue Agave, and that's what it's used for. The current correct name is Agave angustifolia variety tequilana, but succulent growers refuse to use that name.

The yellow-flowered trees in the left and left background are Cercidium floribundum, palo verde. The pink-flowered tree in the background is Olneya tesota, ironwood, a legume tree, growing in a desert wash that runs through my property. The twin palms are the Mexican fan palms, Washingtonia robusta.

Genus Agave is native from the southwestern US into northern South America and the Caribbean. By far the largest number of species occur in Mexico. They are found in many different climate zones. Many agaves are only known from cultivation; they were, and are, economically important as fencing, fiber or food.

Sisal rope comes from Agave sisalana, another species not known in the wild. These economically-important species are regarded as cultivars and strains selected by ancient humans from wild populations. Many food agaves are only known from a few locales.

Common with some human-selected agaves, A. tequilana normally does not produce seed after flowering. Instead, each of the three carpels of each of thousands of ovaries on the inflorescence develops into a small plant, called a bulbil. These are easy to harvest and plant, rendering this plant much faster to propagate than agaves that must be seed-grown. In addition, A. tequilana offsets from the base during its life.

Agaves are monocarpic, meaning they grow for a number of years, flower, and the plant dies. Many offset from the base, so the plant is not lost. Others, however, do not offset, and must be grown from seed.

Mature Agave stems about to flower are loaded with starch. They can be harvested and roasted to produce a fudge-like food. Three days of roasting converts the starch to sugar. Many species were used as food, including this one.

Pre-Contact Americans brewed, and still brew, a type of beer called pulque (POOL-kay) from the sap of many Agave species. The Spanish brought distilling to the New World, and roasted hearts of Agave tequilana can be fermented, then distilled, to produce a delicious distilled spirit.

Agaves make great container plants. They grow to a certain size appropriate to the container, and stop growing. They are extremely sturdy, surviving with very little or no water through the winter, often tolerating freezing night temperatures. Even the largest-growing agaves can be kept in a 4" / 10cm pot for years, looking healthy. This was recognized quickly in Europe after the Contact, and old European artworks show agaves as pot plants.

What I'm getting around to is... I will most likely, by the end of summer, have thousands of small Agave tequilana bulbils that will be easy to mail in a letter envelope. If you want some be sure to let me know. It is a beautiful blue pot plant. It has small teeth along leaf edges, and a stronger spine at the tip of the leaf, but is much less spiny than many other agaves. You can grow it in full sun in summer anywhere in the US or Europe so long as you move it gradually after a winter indoors. It will easily tolerate overnight freezes into the mid 20s F / -6C so you can move your more tender plants in first. It will grow as big as the pot you move it into.

I mentioned palo verde trees in a previous message. This specimen is probably a pure species. It is a volunteer in my garden. I left it because it is in a good place, shading the side of my driveway where I move containers for the summer.

Ironwood (Olneya tesota) is called that because the wood is so hard, and it sinks. It is used extensively for wood carvings in Mexico. It has typical pea-shaped Fabaceae flowers. The standards are pale pink, and the keels darker pink. It is the last native legume to flower here, and only grows in relatively warm spots. Trees are not found in areas with hard freezes. They almost always grow along water courses in the low desert.

Last weekend I drove to visit family in southern California. The ironwoods all along Interstate 10 were in full flower. In 35 years I have never seen this. I did not realize how much variation in color depth exists in the population. I noted the positions of some trees with white flowers, and saw a full range to very dark magenta. Almost all the trees around metro Phoenix have very similar coloration, like the one in my garden.

Sabal uresana is a palm native to the state of Sonora, Mexico. In common with a lot of desert palms, it has a bluish color due to a waxy cuticle that helps conserve water. Most palms have leaves shaped like feathers (considered ancestral characteristics) or fans (considered derived characteristics); Sabal has intermediate, partly-folded leaves termed costopalmate.

Olneya tesota, Cercidium microphyllum, Sabal uresana


Olneya tesota flower spray


Both palo verde and ironwood make great small container plants. They will grow happily in tiny pots, and are easily trained in bonsai style. I will have plenty of seed if anybody wants some. They sprout rapidly during hot weather. I will also have lots of seed of the Washingtonia palms.

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Cleistocactus is a genus from areas of central South America with plentiful spring water. They all have tubular, mostly hummingbird-pollinated flowers, in profusion through the summer, if well watered. They are small-scale columnars, branching from the base. They require less light to flower than many cacti, prefer more water than most to flower well, but will survive with next to none. Most are easy to flower in a 4" / 10cm pot.

In habitat they climb and clamber through shrubs, and can attain some length. Some grow easiest as hanging basket plants. I will show one of these, C. samaipatanus, later, when it flowers.

Cleistocactus ferrari has green-tipped flowers. This flowers mainly in spring.


Cleistocactus paraguariensis has red flowers. This flowers plentifully all summer.


Both these plants came as rooted cuttings from the Huntington Botanical Gardens in San Marino, California.

Cactus taxonomy is in an uproar. Many renamings were done on fewer than 150 base pairs. Everything is to be taken with a grain of salt. The Wikipedia page on genus Cleistocactus contains much wrong information, including a photo of a Neobuxbaumia, perhaps tetezo, misidentified as a Cleistocactus.

I will probably have seed for people who would like some, but it may be Cleistocactus hybrids. Hummingbirds are not careful.

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Echinocactus grusonii is the famous golden barrel cactus. It was known only from the small type locality in Mexico, which was almost totally wiped out by a reservoir. Another locality has been found. Because of its beauty and ease of cultivation, it is probably the most numerous cactus on Earth. Millions are grown in the Canary Islands for shipping around the world. There are selections available with white spines (the "white golden barrel"), no spines ("naked golden barrel") and even curly, twisted spines. In habitat the plants were recorded as reaching over 8 feet / 2.4 meters in diameter. It was also recorded the Aztec used these as sacrificial altars, spread-eagling their human victims over the cacti before cutting out their beating hearts, to produce more blood flow. This was believed to be essential for the sun to rise each day. I grew this plant from a seedling in a 2.5" / 7.5cm pot bought in the late 1980s.

Echinocactus grusonii, the golden barrel cactus


There are a number of species of Echinocactus from the southwestern US into Mexico. The profuse apical wool and dry mature fruits of Echinocactus most easily differentiate the genus from another genus often called barrel cactus, Ferocactus, which has no apical wool and fleshy mature fruits. Smaller seedlings of Echinocactus have no wool, though.

Echinocactus grusonii flowers; same plant as above


Echinocactus Link and Otto is one of the oldest cactus genera. Nobody has argued against it.

In cultivation this genus needs as much sun as possible to look their best. A few Mexican species need a little afternoon shade here in Arizona, but most of them will wither away if not given full sun. The golden barrel is an exception. It survives with poor light, but never looks right. The globular cactus surviving in the lowest rainfall and hottest area of all North America is Echinocactus polycephalus, which is difficult for most people to keep alive. It can be seen along the road from Phoenix to Las Vegas in northwestern Arizona.

Ferocactus schwartzii is from Mexico. It is one of the smaller Ferocacti, and is uncommon in cultivation. This one is about 6" / 15cm across. Notice it has no wool.

Ferocactus schwartzii


Ferocacti also prefer full sun, but will survive with too little light. They are highly susceptible to fungus in acid media, and do much better in alkaline soils. I think this is the reason for their reputation as difficult in cultivation. Standard peat-based cactus mixes are not a good idea for them. Use your clay soil, and water with your alkaline tap water. Avoid organic matter in their potting mixes; organic components decay to acid-producing mush.

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This is Fouquieria macdougallii flowering in my garden.


Fouquieria is a small genus of semi-succulent plants from the southwestern US into Mexico, in the monogeneric family Fouquieriaceae. The one native to the US, from Texas through California, is F. splendens, the ocotillo (oh-coh-TEE-yoh.) It grows far into Mexico. Most of the genus flowers and leafs out opportunistically, after a good rain, during appropriate temperatures. When drought-stressed they drop their leaves. Most species have long, tubular hummingbird-pollinated flowers, but a few have campanulate (bell-shaped) flowers. All have paper-winged seeds ideal for wind dispersal. All but one species are typical summer growers.

The ocotillo looks like an upright whip, with a very short trunk, and numerous extremely long stems rising to perhaps 25 feet. It has tubular orangey-red flowers in dense clusters at the tips. Other species, such as this F. macdougallii, grow in the form of more typical trees, and have bright red flowers.

A few have white flowers. One of these is the famous boojum tree of coastal northern Baja California, F. columnaris, formerly known as Idria columnaris. The Mexican name is cirio, candle, and it looks like a white carrot root growing upside down. I encourage you to look up photos online. The boojum is one of very few North American mediterranean climate, winter-growing succulents, from the northwestern Baja fog desert. What would be the hottest part of the year, early summer, is moderated there by dense daily fogs. Another white-flowered species with a growth habit similar to the boojum is F. purpusii, from Oaxaca. It is a summer grower. Being CITES I (though there are many millions in habitat) it can be hard to find.

The red-flowered ones (and F. purpusii) grow great in humid, warm summers, and can be kept dry and leafless over the winter. They are favorites of succulentists for their interesting stem colors, streaking and spines, though most need a fairly large container to flower.

The boojum, though, rots easily with warm summer nights and humid warmth. It is hard to keep alive in the midwestern US, and on the valley floor in metro Phoenix. It grows well at higher elevations around our city. It is not hard to grow in cool climates like northern Europe, where summer resembles a Baja winter. But all of them need maximum light all year.

I didn't show my whole plant because it would be lost against the shrubs behind it. But F. macdougallii grows with a short trunk peeling bark and branches above. It is marginally hardy here. Severe winters kill branch tips and prevent spring flowering. I don't get seed on my plant, but other growers here in Phoenix get it regularly. With regular summer water it flowers in flushes through warm weather.

They are easy from seed. Sprouting requires surface sowing, boggy wet soil and full sun. The boojum does best with moderate sprouting temperatures, but the others like it as hot as possible. Seedlings must remain in full sun after sprouting to avoid damping off.

Mammmilaria is a large cactus genus, from the US to northern South America, with by far the most species in Mexico. They tend to be small and clump, and many have really nice flowers.

They have been popular with cactophiles for centuries. Mammillaria johnstonii is a Baja California plant rare in cultivation. I think this is because it doesn't have fancy spines, and the flowers are small and nondescript. Many mammillarias are hard to grow with hot summer nights, since they come from the central plateau in Mexico. I have to be careful watering a lot of them during our hottest time of year. The Baja ones tolerate any amount of heat, so they do well here in Phoenix.

Mammillarias are likewise easy from seed. Like most cacti, their seedlings are not very succulent, and must remain very moist for the first few years, without drying out. They also require surface sowing and light to sprout, but standard cool white fluorescent lights are adequate for the first few years.

Mammillaria johnstonii


This plant was grown from seed by the late Debra Korobkin, a long-time member of the Central Arizona Cactus and Succulent Society. She loved seeing plants in habitat. Our permanent show trophy for Best Arizona Native Plant is named in her memory. She passed away in her early 50s of a heart attack while relaxing in a natural desert hot springs after a day exploring.

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Opuntia basilaris, the beavertail prickly pear


Opuntia basilaris is native to northern Arizona, into California, Nevada and Colorado. I think maybe New Mexico as well, but I'm not sure. If you've visited the Grand Canyon you've seen it growing on the rocks, on both rims. It needs sun, so it does not grow into the forest. It is known as the beavertail prickly pear cactus because of the shape of the stem segments. Like most cacti from very cold climates, it is a low grower. Here in Phoenix, where it is not native, it forms much wider clumps than in habitat. It has beautiful flamingo pink flowers that can be seen for a long distance.

There are a few populations with pure white flowers. It is among a group of genus Opuntia having dry fruits at maturity. Most Opuntias have fleshy fruits, found tasty by most mammals and birds.

This species will rot with too much summer water. A rainier than normal Phoenix summer may cause rot. It will not flower without full winter sun. I have several clumps in my front garden, cuttings of the same clone. They get full sun all day in summer, but varying degrees of shade in winter. This, the one getting the most winter sun, is the only clump that flowers. Most members of genus Opuntia are easy in cultivation in unsuitable climates, but this one is not.

Opuntioideae is one of the subfamilies of cactus. Cacti tend to have long solid spines at each areole. Almost all opuntiads have a second type of spine, a very tiny, thin, barbed and NASTY thing called a glochid. Opuntiads are found in North and South America. Stem segments of genus Opuntia are flattened, and many people think of them as leaves, which they are not. Larger opuntiads with cylindrical stems, colloquially "cholla" in Spanish, are in genus Cylindropuntia in North America, and Austrocylindropuntia in South America. Most opuntiad flowers are thigmatotropic, which means the stamens curl over when touched. They brush pollen on the backs of visiting bees. This is easy to see in almost any Opuntia flower if you stick your finger into the center.

Neoraimondea herzogii / Neocardenasia herzogii flowering in Phoenix, Arizona, USA


Neocardenasia herzogii is a large columnar cactus from east of the Andes. It does very well here in Arizona. I have one of the few specimens large enough to flower. I planted this from a 3 foot / 1 meter tall spear in 1997. It is about 20 feet / 3.2 meters tall, and is in its third year of flowering. I have a photo someplace from 1997 of me standing next to the plant in the container. I will try to find it and scan it.

Across the Andes grows genus Neoraimondea. The two genera were originally named separately because botanists thought the Andes were very old, which they are not. They are now both considered Neoraimondea, the older name. This plant is still commonly found under Neocardenasia, so I give both. It makes a good cactus for those with cold winter climates because it is rigidly upright for a long time, it likes warm, humid summers, and in habitat it gets no winter water.

Neoraimondea herzogii tolerates Phoenix frost; its Peruvian relatives do not. Interestingly, this plant has some of the longest spines in the cactus family when young, over 10" / 25.5cm. When the plant gets above about 8 feet / 2.4 meters it becomes completely spineless. It is thought a now-extinct mammal was a predator on the plant.

One defining feature of a cactus is the areole. This is the fuzzy spot from which can grow spines, stems or flowers. All cacti have them; sometimes, in the epiphytes, they are so reduced a microscope is needed to see them.

An areole is a reduced branch. Most cacti start out with two meristems per areole. One develops into spines, which are modified leaves. The other meristem can develop into flowers, or another shoot, but not both. Neoraimondea is unusual in that the second meristem on flowering areoles develops into a short shoot, and the plant flowers from these shoots year after year.

The last photo is the front of my house, showing the tall Neocardenasia. When I bought it in 1986 the only plants present were the three visible palms: two Mexican fan palms, Washingtonia robusta, in the back garden; and a female date palm, Phoenix dactylifera, in the front. The front garden was like a gravel parking lot, with two large boulders. I planted everything else.

You can see the Neocardenasia, the tallest columnar cactus. The Fouquieria macdougallii mentioned in a previous message is between this cactus and the street, but not easily seen in this photo.

[Leafmite]

This is a very nice post.

[WaterWitchin]

Love it. I had relatives in Phoenix AZ, traveled there often, stayed for summers at times. Was always fascinated by the difference of plants there, as opposed to my Kansas background.

Thanks so much for the info, AND the memories.

[DeaC]

TY. Your knowledge is as varied as the landscape and obviously extremely adaptable. Visiting your great state will be on my bucket list. Have a thorny day!

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The saguaros in metro Phoenix began opening flowers in the last 10 days. They are just starting in the metro Tucson area, which is some 1000 feet / 300 meters higher in elevation.

The saguaro is Carnegiea gigantea. I mentioned the genus Neobuxbaumia in a message above. This is a genus of around 10 species of tall columnars, found in Mexico.

If you look at photos of the Neobuxbaumia species that branch (some don't), you will find they look very much like saguaros from a distance, in terms of the roundedness of stem apices and proportions of stem width to mature height. These are not often used as diagnostic characteristics in cacti, but they are good ways for amateurs to tell many apart.
Most Neobuxbaumia species bear their large flowers in clusters from adjacent areoles right at the apex of stems. Large apical flowers are unusual among North American columnars; most of them have flowers a little farther down the stem, sometimes quite a way down the stem. Saguaros also bear flowers in this manner.

Some people think Neobuxbaumia should be sunk into Carnegiea, which is the older name. I don't know what the DNA studies show.

It would certainly become a topic of discussion were it to happen. Buxbaum wrote an important monograph on cacti. Carnegie was a wealthy businessman who turned to philanthropy late in life. He provided initial funding for the Carnegie Desert Laboratory, which is now known as Saguaro National Park in Tucson, Arizona.