delightful dudleyas 2012

Download Delightful Dudleyas   2012

If you can't read please download the document

Post on 15-Jan-2015




2 download

Embed Size (px)


This lecture was given in March, 2012 as part of the California native plant gardening series ‘Out of the Wilds and Into Your Garden’.


  • 1. Out of the Wilds and Into Your GardenGardening with Western L.A. County Native PlantsProject SOUND 2012 (our 8th year) Project SOUND

2. Delightful Dudleyas C.M. Vadheim and T. DrakeCSUDH & Madrona Marsh PreserveMadrona Marsh PreserveMarch 3 & 6, 2012 Project SOUND 3. We already know that California (andBaja California) plants are special Our Mediterranean climate requires that plants adapt to summer drought. One common adaptations is succulence. Modified tissues store large amounts of water, making the plant part appear fleshy, succulent, or swollen. Species in various plant families and genera have independently evolved succulence as a mechanism for conserving water and survival in arid environments. There are an estimated 10,000 succulent plant species throughout the world Project SOUND 4. The Live-forevers: genus Dudleya Named for William Russel Dudley (1849- 1911), first professor of botany and head of the Botany Department at Stanford University ~ 40 species; native to the arid western United States (in particular, Southwest/ Northern California and Oregon), Baja California. Very similar in appearance to other Stonecrops (sempervivum; sedum; echeveria). Often grow in stone crevasses or sand dunes with little or no organic soil. Long-lived (to 100+ years for some species) hence the common name Project SOUND 5. The Stonecrop Family: Crassulaceae~ 1500 speciesMost genera exhibit some leaf succulenceMany species are used widely as garden and house plants Examples: The genus Crassula includes the well-known Jade Plants and other small sub-shrubs, choice minatures and mat-forming plants.Echeverias Cotyledon includes interesting shrubby species with succulent stems and leaves. Some species have showy tubular yellow, orange or red flowers. Echeverias are often used in rock gardens and indoor plants. Kalanchoe includes plants with showy flowers. Sedums are well known for hardy mat-forming Stonecrops which provides useful flower color in the garden in late summer and early autumn. Kalanchoe Project SOUND 6. Crassulacean acid metabolism (CAM) Found in 3-4% of plant species;at least 26 angiosperm families Nearly all are succulents(thick, fleshy leaves andstems) Nearly all are from deserts orother hot-summer areas Is an extremely importantwater-conservation strategyfor plants in hot, dry climates 7. All plants have the ability to convertcarbon dioxide to sugars, usingenergy from the sunThe process of photosythesis Project SOUND 8. Gases and water vapor enter and exitplants through stomata Project SOUND 9. CAM - observations Stomates - open atnight; closed duringday (inverted stomatalcycle) CO2 uptake high atnight; low during day Acid content of cells highest at dawn; lowestat dusk Conclusion: CAM plantsstore Carbon as an acidat night 10. CAM plants like Dudleyas are adapted to hot, dry climates Dudleyas only open their stomata at night to take up carbon dioxide. They keep their stomata closed during the hot days, allowing the plant to conserve tremendous amounts of water The plant assimilates the carbon dioxide at night and converts it to a variety of organic acids. In the morning when the stomata close, the organic acids break down and carbon dioxide is released. With the energy of the new days sun light, the plant converts the carbon dioxide it has been accumulating all night into sugars. Before being permanent CAM photosynthesizers, CAMs were probably started intermittently switching to CAM photosynthesis during times of drought and low rainfall. Eventually those species evolved into species that solely depended on CAM photosynthesis Project SOUND 11. Dudleyas can be used in several ways in the home garden Project SOUND 12. In terms of their garden potential, you can think of Dudleyas as belonging to one ofthree categories The Dudleya divas Often larger in size Showy (exuberant) flowers Very attractive foliage The groundcover Dudleyas Medium to small size Readily spread, forming a mat The Pretty in a Pot Dudleyas Medium to small size Unique flowers or foliage Project SOUND 13. Dudleya divas showy accent plants Project SOUND 14. Chalk Dudleya Dudleya pulverulenta ssp. pulverulenta Project SOUND 15. Chalk Dudleya Dudleya pulverulenta ssp. pulverulenta Coastal regions from San Luis Obispo south into Baja Locally in Santa Monica Mtns., western San Gabriels Rocky cliffs and canyons below 3000 feet,3295,3327,3329 Coastal sage scrub, chaparral Project SOUND 16. Chalk Dudleya is very Echeveria-like Size: 1-2 ft tall 1-2 ft wide (flower stalks wider) Growth form: Evergreen succulent Becomes somewhat dry insummer Foliage: Leaves flat, end in sharp tips completely covered with a mealywhite powder - hence"pulverulenta" or "powdery." Stem (caudex) becomesthickened with age more sothan other species Project SOUND 17. Taxonomic confusion: is that anEcheveria or a Dudleya? a%20main.htm Echeveria Dudleya Quite similar-looking; but with a few important differences Several local species were formerly included in Echeveria: Canyon Live-forever Dudleya cymosa Chalk Dudleya Dudleya pulverulenta Ladyfinger Dudleya Dudleya edulis Project SOUND 18. Dudleya flowers are slightly different Dudleya flowers arise from somewhere near the bottom ofthe rosettes normally (rarely from the rosette center asmost Echeveria flowers do). Dudleyas & Echeverias do not form hybrids between the 2genera; Dudleyas only interbreed with other Dudleyas Project SOUND 19. But the real difference and the most important for gardeners relates to their history Dudleyas Native to the Pacific Plate Adapted to rainy winters & hot, drysummers Winter-growing; summer dormant Can kill them with too much summerwater Echeverias Native to the North American Plate Adapted to rainy summers & dry winters Summer growing; winter dormant Can kill them with too much winter waterThe two genera have been separated for longenough that each is very well adapted to itsown environment Project SOUND 20. Soits recommended to NOT combine both in the same part of the garden Summer watering of Dudleyas should be very occasional: they are very summer water-wise compared to Echeverias Most Dudleyas & Echeverias do best inwell-drained soils; gravelly/sandyDudleya virens ssp hassei The roots of some Dudleya species donot absorb moisture well in the highheat; water simply rots the roots(susceptible to root rot fungi). Treat as Zone 1-2 (water only severaltimes a summer & not at summers end) Dudleyas in very well-drained soils(sandy) or in pots should be treated as 2 Project SOUNDp?plant_id=538 21. Dudleyas can also rot from the crown or leaves, particularly if water is left sitting on the delicate leaves (some are more sensitive than others). Dudleya virens ssp hassei Either avoid getting water on theleaves, or plant them at an angle so thewater runs off. In nature, many species grow naturallyon cliff faces and steep slopes sowater cannot sit on these plants. Excess water also attracts snails andslugs which love Dudleyas Bottom line: best to not combine Dudleyas with succulents that have very different water requirements (Echeverias; Sedums; etc.) SOUND Project 22. Give them whatthey like Plant them in/near rocks Naturally occurring Local boulders brought in toDudleya pulverulenta add interest Plant them on slopes orplant the rosette at an anglerather than horizontal Water only occasionallyduring summer Zone 1-2about right No overhead water insummer virens ssp. hassei Project SOUND 23. Flowers are like no others: dramatic! Blooms: spring/early summer; typical for Dudleyas Flowers: On long flowering stalks plan accordingly Note hummingbird-plantfeatures: Red color; Shape; Flowers held away fromplant to allow access Heavy duty, sweetnectar Project SOUND 24. Be creative with rocks& Dudleyas Sometimes man-made stonestructures are perfect placesfor Dudleyas Project SOUND 25. * Silver Dollar Plant - Dudleya brittonii Project SOUND 26. Silver Dollar Plant - Dudleya brittonii Native coastal areas of the Pacific side of Baja California between Tijuana & Ensenada and on Isla Todos Santos On cliffs and hilly areas in lava rock and other very porous soils. Project SOUND 27. Nathaniel Lord Britton the specific epithet honorsNathaniel Lord Britton(1859-1934), botanist andfirst Director of the NewYork Botanical Garden. Dr.Britton is also famous forhis collaboration withJoseph Nelson Rose of theCarnegie Institute on Thehttp://www