Accepted Scientific Name: Dudleya saxosa subs. collomiae (Rose) R.Moran
Madroño 14: 108. 1957
Dudleya saxosa var. collomiae (Dudleya saxosa subs. collomiae) Photo by: Diego Armentano
Origin and Habitat: USA, central Arizona. Apart from central Dudleya pulverulenta ssp. arizonica, this is the only taxon of Dudleya occurring in Arizona.
Altitude range: 400–3000 metres above sea level.
Habitat and ecology: Rocks and hillsides, Lower and Upper Sonoran Zones, sometimes growing together with Graptopetalum rushyi and Agave toumeyanaSN|576]]SN|576]] ssp. bella.
Synonyms:
See all synonyms of Dudleya saxosa
Common Names include:
ENGLISH: Live-forever, Rock Live-forever, Gila County Live-forever, Rock Echeveria, Echeveria
Description: Dudleya saxosaSN|32637]]SN|32637]] subs. collomiae (firstly described as Dudleya collomiaeSN|32643]]SN|32643]] by Rose in 1934) is a succulent perennial herb with a short caudex 1.5-3.0 cm thick, cespitosely branched to bear 5-10 rosettes. It is a well-isolated polyploid subspecies, similar in shape to the diploid subsp. aloides, differing mainly in its larger flowers. The flowers of Dudleya collomiaeSN|32643]]SN|32643]] are yellow including petals and anthers; flower parts have a light pink tinge when immature. Dudleya saxosaSN|32637]]SN|32637]] ssp. aloides (panamint liveforever) has lavender to pink flowers.
Derivation of specific name: This member of the Crassulaceae family was given this name by Mrs. R. E. Collom, who discovered the taxon.
Caudices: Short, 1.5–3 cm in diameter, cespitosely branched to bear 5-10 rosettes.
Rosettes. With 12 - 20 leaves.
Leaves: Leaf blade, succulent, erect or spreading, glaucous when young (not farinose), oblong-lanceolate, flat on upper surface, rounded beneath, acute, 5–15 long, 1–2.5 (basally 1 – 2.5) cm broad, 2–6 mm thick.
Inflorescences: Floral shoots red, 5–12-leaved, 15–40 long, 3–6 mm in diameter, scorpioid. Cincinni (branches) 4–15-flowered, 3–12 cm long. Pedicels 5–20 mm long.
Flowers: Calix 5 - 8 mm in diameter, lobes (sepals) 4 - 7 mm long. Petals 12-16 (-20) mm long, 3-4 mm wide, usually bright yellow, tube 1-4 mm long.
Blooming season: Spring (March-May).
Fruits (follicles): Unripe follicles erect.
Chromosome number: 2n = 136.
Subspecies, varieties, forms and cultivars of plants belonging to the Dudleya saxosa group
Bibliography: Major references and further lectures
1) Reid V. Moran Dudleya saxosa (M. E. Jones) Britton & Rose subsp. collomiae (Rose) Moran [family CRASSULACEAE] in: “Flora of North America”, Vol 8, retrieved 01 March 2016 from <http://plants.jstor.org/compilation/dudleya.collomiae>
2) Urs Eggli “Illustrated Handbook of Succulent Plants: Crassulaceae” Springer Science & Business Media, 01 January 2003
3) Forrest Shreve, Ira Loren Wiggins “Vegetation and Flora of the Sonoran Desert”, Volume 1 Stanford University Press, 1964
4) Urs Eggli, Leonard E. Newton “Etymological Dictionary of Succulent Plant Names” Springer, Berlin/Heidelberg 2010
Cultivation and Propagation: This slow growing specie is often grown and makes an attractive plant. It is much admired but less easily grown than some others. Grow it as a house or conservatory plant in a porous mix, or as a garden perennial where winters are mild and summers dry. Dudleyas are hardy in USDA Zoned 9-12, the plant is highly heat and drought tolerant during the summer months and prefers moist cool winters. Powdery white leaves make these plants standouts, but avoid touching them as they are easily and permanently marked by finger marks. All of the plants in the Dudleya genus are known to live up to 100 years.
Soil: They do best in very well-drained, sandy or gravely soil. As an ornamental it is also grown in containers where it stays smaller than its outdoor brethren. In pots they need a very porous mix soil (e.g. 2 parts peat moss to 1 part loam to 1 part of pumice).
Exposure: It requires ample sun, but provide midday shade where summers are hot. The quality of light is much more important than the quantity, the plants contain farinose powder which makes them really effective for ultraviolet reflectivity. Low light situations might be stressful and create a susceptibility to mealy bug infestation.
Watering: Dudleyas are summer-dormant winter growers that require fresh air, exceptionally well- drained soil, and don't water them in summer even if they appear crisp and miserable; they're dormant and unused to summer rainfall. However, they do appreciate an occasional misting suggestive of coastal fog (provide water in spring and autumn). In the summer the roots are unable to absorb the water so any excess of water simply rots them because of their dormant state.
Maintenance: Remove spent flower stems for appearance. The older leaves of Dudleyas wither but remain attached to the stem. Whether or not they should be removed is disputed, but they provide a hiding place for pests and some growers preference to remove them.
Uses: This can become a beautiful pot plant with pretty inflorescences with the right care.
Propagation: Dudleyas has been found to be propagated through both seed and vegetative, although vegetative propagation by offsets in spring or early summer is not only more popular but it is much easier to do. Dudleya should be planted at an angle. This prevent s the buildup of water in the leaves, which may lead to the leaves rotting. The vegetative propagation process needs to be done with temperatures reaching 21 degrees C. Let dry the cutting for about five to ten days and put the the cutting into the rooting compost (2 parts perlite and 1 part cactus potting mix). After finishing this you then place the pot in a warm, sheltered, but very bright filtered light area with no direct sunlight, you do not want the leaves to dehydrate. During the rooting period make sore to limit water, the rooting will take around 2 weeks, after roots transplant into the growing container. One thing to remember when rooting cuttings, overhead watering is not good for it, apply only to the soil line. The seeds do not need to be covered but do need a moistened soil for germination. Placing them into a mist house at an optimal 20-21 degrees Celsius with sufficient lighting resulting in germination. Germination occurs in just two weeks.
Dudleya saxosa subs. collomiae (Rose) R.Moran
