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Plant Highlight: Dudleya cymosa ssp. paniculata
by Brian Kemble
Area of occurrence
The genus Dudleya has a conspicuous presence along California’s shoreline, ranging from coastal southern Oregon in the north all the way down to Baja California in the south. However, there are species that occur farther inland as well, and one of these is Dudleya cymosa, with an extensive distribution along the Coast Ranges from Lake County down to the mountains around L.A., as well as on the western side of the Sierra Nevada from near Chico southward. As might be expected from a plant occurring over such a large area, D. cymosa has a lot of variability (in terms of its size, its flower color, and its leaf color), and some forms are distinctive enough that they have been named as subspecies. An example is Dudleya cymosa ssp. paniculata, known as the Diablo Range dudleya. It grows on Mt. Diablo and Mt. Hamilton in the Bay Area, and southward through much of San Benito County.
About the plant
D. cymosa ssp. paniculata is generally stemless or short-stemmed, and it is often single-headed, though it may sometimes branch to make a several-headed clump. Its leaves are grouped in a rosette with a diameter of 2⅓ to 6 inches (6 to 15 cm), or occasionally even more than this. The leaves may be as short as 1.2 inches (3 cm), and on robust specimens as much as 4 inches (10 cm), with a width of .2 inch to .8 inch (.5 to 2 cm). The leaves are more or less lanceolate (widening from the base to the middle, and then tapering to a pointed tip), and slightly cupped rather than flat. Sometimes the leaves are smooth and dull green to gray-green, but often they are whitened with a powdery coating to some degree, especially the newer leaves at the center of the rosette.
About the flowers and fruits
May and June are the heart of the flowering season for Dudleya cymosa ssp. paniculata, though flowering may commence as early as April and end as late as July. The inflorescence varies in height from 2 to 10 inches (5 to 25 cm), and it usually arches upward alongside the rosette rather than going straight up. It branches and re-branches, with 4 to 10 flowers produced at the end of each branch, opening in sequence from the lowest to the uppermost. Each flower has a pedicel from .12 to .47 inch long (3 to 12 mm) and is clasped at its base by 5 more or less triangular sepals, these being green to greenish-yellow. The 5 petals are on average about .4 inch long (10 mm) and pale yellow to almost white, or sometimes tinged with green. The petals are conjoined into a tube at their bases, holding nectar within, and they curve outward at their tips. Within are the 10 stamens, with their pollen held at the mouth of the flower. At the flower’s center are the 5 carpels, sticky at their tips so that pollen will adhere when provided by a visiting hummingbird or insect. When successfully pollinated the carpels expand, and at maturity they yield a large quantity of tiny seeds. When the carpel dries and splits along a lengthwise seam, the seeds are dispersed by the wind.
Plants in cultivation
As is often the case with succulents, good drainage is essential for growing Dudleya cymosa ssp. paniculata. As an inland species, it puts up with high summer temperatures better than many of its coast-hugging relatives, though its rosettes shrink markedly over the summer months, when it does not produce any new leaves. With the arrival of the first rains in the fall, it begins growth anew. In a garden setting, it can take a little water during the summer months, but care should be taken that it does not get too much. Plants tend to do best in dappled shade or morning sun if grown in hotter inland gardens. Like many Dudleya species, this one is highly adapted to a Mediterranean climate, and it is difficult to grow it successfully in places with high summer humidity.
Dudleya cymosa ssp. paniculata growing on Mount Diablo.
