There historically were two versions of this rosette succulent, a powder-dusted bluish white one and a powder-free pale green one. Different looking but the flower is almost identical so they were lumped. Both white and green forms are found in northwestern Baja California distributed along the immediate vicinity of the coast, roughly from Rosarito to Puerto Santo Tomás. This location has an exceptionally mild, often foggy climate with dry summers and wet winters.
In cultivation and in nature, these plants obey a natural cycle of summer dormancy and winter growth, so they will look quite different depending on the time of year. They like excellent drainage (they grow on almost pure rock in habitat) and will do well in a surprisingly broad range of containers, being dwarfed by smaller ones and exuberant in larger ones, as long as they are provided strong light. Very drought tolerant (months of summer drought is normal in habitat).
Here in habitat they flower from early winter through early summer, roughly, depending on water availability. Small, tubular flowers borne in clusters above the plant attract hummingbirds. Will grow a stem (covered in dead leaves and flower stalks) over time. Normally solitary, especially the white northern form (ie. only from seed), but there is a green-leaved population toward the south of the plant's range which branches dichotomously and forms impressively large clusters over time. Individual rosettes of either form can easily be grown from short-stemmed cuttings.
This plant is self-seeding in my container garden. Seedlings can be reliably transplanted when they are thumbnail-sized and can grow to full size within about one season. To collect the seeds (very fine, <1mm): wait until the entire inflorescence is brown (down to the last flower) and then cut it at the base, and shake inverted for a couple of minutes over a white plate.
The white form of D. brittonii may look vegetatively similar to D. pulverenta, but its flowers are different (among other ways greenish yellow, not red). D. brittonii can be one of the parents of the naturally occurring hybrid D. x semiteres, along with D. attenuata orcutti. The green form of D. brittonii may be difficult to resolve from D. ingens, which grows further to the south, especially when not in flower.
Recently (March 2023) the green plants formerly called D. brittonii have been given two new names. The powder dusted plant is still called Dudleya brittonii but the green ones are called
Dudleya (Dudleya reidmoranii) or
Dudleya (Dudleya josedelgadilloi).
There are various subtle differences between the two new green species, but the most obvious way to tell them apart is by looking at the orientation of the flowers on the inflorescence. Racemes pointing downward indicate reidmoranii and racemes pointing upward indicate josedelgadilloi. Geographically these forms overlap with each other and with brittonii, but only the white brittonii is found exclusively toward the north of their range, in an area centered around La Mision.
https://bioone.org/journals/ma...