Sonoran Desert / Arizona Species?

oooOIOooo via pbs pbs@lists.pacificbulbsociety.net
Tue, 28 Dec 2021 12:16:34 PST
Ian wrote
> A new member here interested in seeds/bulb sources
> for Sonoran Desert species, along with any tips on
> how to get them to thrive in Central Phoenix.
> Amoreuxia gonzalezii
> Amoreuxia palmatifida
> Calochortus kennedyi
> Hesperocallis undulata
> I know with A. gonzalezii, it may be happier in a
> shady pot, but I'd ideally like to have any/all in
> the ground. Soil is fairly clayey.

Hello Ian,
There are also the very widespread and easy to grow Calochortus nuttallii and Dichelostemma capitatum, which has been called Dichelostemma pulchellum. I think there are one or two other Calochortus in Arizona at higher elevations.

Amoreuxia are summer monsoon growers. They may rot if you water too early. They like lots of water when in growth, and flower profusely. Sprout seed when the monsoon arrives.

The Calochortus and Dichelostemma are winter-rainfall species. Keep them moist and sunny all winter. Let them dry when they finish flowering.

Hesperocallis undulata is an opportunistic grower, depending on rainfall. I have seen rosettes in leaf in summer and in late winter, in different places.

Right now is the time to plant seed of Calochortus, Dichelostemma and Hesperocallis - late October would have been better.

Calochortus and Dichelostemma I've seen in Arizona habitats, or that occur in habitat I'm familiar with, generally grow in very rocky or sandy soil on slopes, with not much soil over the underlying rock. Sometimes Dichelostemma grows in small pockets of sand in cavities in rocks.

Hesperocallis mostly occurs in deep sand. This may be in or alongside intermittent streams or dry lakes, or close to these.

I tried growing both Amoreuxia species in 5-gallon pots of heavy, fine clay and sand screened from a wash; they only grew well for a few years. My pot of A. palmatifida sprouted weakly this spring, but did not flower. It soon died down. I don't know whether they're still alive. Both species gave seed only the first year they flowered in those pots.

The Desert Botanical Garden gift shop in the past has carried seed of the Dichelostemma. You can probably find it from other sources if you search online. Members of both the Central Arizona Cactus and Succulent Society and the Arizona Native Plant Society grow it in their gardens; it is a reliable native plant that flowers every spring if it gets enough winter water. The CACSS meets the last Sunday of most months at the DBG. Many members grow both winter- and summer-rainfall bulbs, providing seed and plants to the club auctions. We are friendly and welcome people. If you can't find seed I'm sure a member will save some for you this coming Spring, if you come to a meeting and ask.

The species other than D. capitatum are not always easy to find. Searching online may help. I provided seed in 2020 to the PBS seed bank of Hesperocallis from Ford Dry Lake in Riverside County, California; I did not see any plants there in spring 2021 (nor in any other of the past 38 years I've driven by that lake.) This winter promises good rainfall, so they might reappear in spring 2022, and I will again collect seed if possible.

Hesperocallis undulata is easy to grow but not to flower. It grows like a weed in almost any sized pot, provided the roots don't get too hot nor dry out when in leaf in the summer. Many people report it is difficult to get it to resprout if it is allowed ever to go dormant from drought. It's an Agave relative.

I can offer only speculation about growing it. It is a plant from regions with little or no winter frost. It grows in deep sand. I know people who have dug 6 feet into sand and have been unable to reach the plant below a surface rosette. The sand kept collapsing so they could not dig deeper. Populations in or near intermittent streams, where water occurs regularly, will produce leaf rosettes every year. This might be in spring after winter rains, or summer after summer rains. The vast population around Ford Dry Lake has only sprouted once in the last 38 years I've driven by. That followed some wet winters. I suspect plants far from streams may lie dormant for decades awaiting a plentiful rainfall.

The above leads me to think the bulbous buried stem will be cooler than surface temperatures, even on very hot days. I suspect water must reach the stem in a good quantity to trigger production of a rosette, which might be at any time of the year. Leaf rosettes are puny compared to the size of the inflorescence, fruits and seeds. I suspect in habitat they require several to many years of bearing sterile leaf rosettes to gather enough starch to produce one inflorescence and fruit. And being Agave relatives, I suspect rosettes are monocarpic, flowering only once, then dying, leaving offsets behind.

I'm going to move my Hesperocallis seedlings into very deep, well-insulated containers I will make out of 4" diameter PVC pipe standing on end. I'm going to grow them in sand. I will keep a few as foliage plants in standard pots as backups. I don't know whether this will work at all, and it might take many years to find out.

One of these years I need to get to a population of C. kennedyi I know beside a road an hour out of Tucson, during fruiting season, but I've never made it. Maybe if I retire.

***
Michael Kent chimed in
> Do I want to know why Amoreuxia gonzalezii
> is known as Santa Rita throwup weed?

I suggest you apply for a PBS research grant.

Leo Martin
Phoenix Arizona USA
Zone 9?
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