Prunus subcordata
| Pacific plum (Prunus subcordata) | |
|---|---|
| Scientific name | Prunus subcordata |
| Common names | Pacific plum; Klamath plum; Sierra plum; Oregon plum |
| Genus | Prunus |
| Family | Rosaceae |
| Order | Rosales |
| Native range | Southern Oregon through central California |
| Growth habit | Deciduous shrub or small tree; often thicket-forming |
| Fruit | Red-purple or sometimes yellow, sour stone fruit |
| Flowering | April |
| Fruit ripening | Late summer to early autumn |
| Pollination | Insect-pollinated flowers; cross-pollination may be needed in some selections |
| USDA hardiness | Zone 7 in the Oregon State account; PFAF lists Zones 6–9 |
Prunus subcordata, commonly called Pacific plum, Klamath plum or Sierra plum, is a deciduous native plum of southern Oregon and California. It grows as a shrub or small tree and can form thickets. Kew accepts Prunus subcordata as the species name and lists Prunus oregana and several subspecific or varietal names among its heterotypic synonyms.[1] Oregon State University describes the plant as reaching about 7.5 m, with white flowers that turn pink and edible reddish-purple fruit that is sometimes yellow.[2]
The name Sierra plum needs care in plant identification: it is also used for the unrelated Asian plum cultivar ‘Sierra’. A public grower discussion distinguishes that cultivar from the native Prunus subcordata and includes individual, context-limited reports of fruit quality and nursery labeling; those reports should not be treated as general descriptions of the species.[6]
Description[edit | edit source]
Pacific plum varies from a shrub to a small tree and commonly produces thickets. In its native range it occurs along streams, in canyons and on hillsides, as well as in open pine forest. The historical Oregon account found larger plants on deeper sandy loams where water was ample, while exposed rocky sites supported smaller plants.[3] The plant is deciduous and its white flowers become pink as they age. Fruit is usually red to purple, although yellow-fruited forms have been recorded; Oregon State gives a typical width of 1.5–2.5 cm, while the PFAF account describes fruit up to 3 cm.[2][4]
The species has also appeared in plum-breeding discussions as Southern Oregon germplasm with possible value for fruit, disease-resistance and climatic-adaptation traits. That breeding review is context for use of the species in breeding, not evidence of a currently available cultivar or of a guaranteed trait in seedlings.[7]
Cultivation[edit | edit source]
Soil and water[edit | edit source]
In the wild, larger growth is associated with deeper sandy loams and ample water, while the species also occupies rocky hillsides and canyons.[3] For cultivation, Oregon State recommends moist, well-drained soil and full sun; the PFAF cultivation account likewise recommends a moisture-retentive but well-drained loam and cautions that excessive lime may cause chlorosis.[2][4] The practical target is steady moisture with drainage rather than either prolonged saturation or a sharply drying root zone.
Sun and humidity[edit | edit source]
The species occurs in open pine forest, canyons and exposed hillsides, and Oregon State recommends full sun.[2][3] Give a planted tree an open, well-aired position with enough light for flowering and fruiting. Its natural range includes both moist streamside settings and dry, exposed sites, so local irrigation should follow soil drainage and seasonal rainfall rather than a fixed watering schedule.
Seasonal changes[edit | edit source]
Pacific plum is deciduous. PFAF records flowering in April and seed ripening in August–September; the Oregon field bulletin describes fruiting in late summer or early autumn.[4][3] Keep the root zone supplied with moisture during active growth and fruit development while maintaining drainage, then account for the leafless dormant period when planning irrigation. Fruit set and bearing are affected by weather, insects, soil, crop load and plant condition, so a calendar date is only a starting point rather than a guaranteed harvest schedule.[3]
Propagation[edit | edit source]
Seed is reported to need 2–3 months of cold stratification. The PFAF account warns that germination can be slow and may sometimes take 18 months; it also lists half-ripe heel cuttings in July or August, softwood cuttings in spring to early summer, and spring layering as possible methods.[4] These are compiled cultivation instructions rather than a replicated, species-specific propagation trial, so seed lots and cutting material should be treated as variable.
The historical Oregon work included rootstock and vegetative-propagation investigations and documented variation among seedlings.[3] It does not justify treating an unnamed nursery label or a single seedling as a stable cultivar. Verify the identity and provenance of purchased plants, especially where “Sierra plum” is used without the scientific name.[6]
Flowering, fruiting, and harvest[edit | edit source]
The flowers are described as hermaphroditic and insect-pollinated.[4] In controlled selfing and crossing work on selected trees, Hammers concluded that the selections studied probably required cross-pollination and recommended planting two or more different selections, while explicitly limiting the conclusion and calling for further work.[5] Planting genetically distinct, correctly identified trees is therefore a reasonable precaution where fruit set matters, but the historical study does not establish universal self-incompatibility for every population.
The Oregon Experiment Station bulletin records flowering in the second or third orchard year, but generally little fruit until about the fourth year when trees were making the desired growth. That historical schedule varied with location, soil drainage, weather, crop load and plant condition and should not be used as a fixed promise for modern trees.[3] Fruit is reported in late summer to early autumn, with PFAF giving August–September seed ripening.[4]
Fruit and uses[edit | edit source]
The fruit is edible and usually sour, with some astringency; PFAF notes that the best forms can be pleasantly acid with only slight astringency.[4] The Oregon account records red or purple fruit and an older description of a yellow-fruited Mount Shasta type, although the investigators did not locate that type in their survey.[3] This variation is a reason to keep fruit descriptions tied to a documented tree or selection rather than assuming that every plant will have the same color or flavor.
The fruit can be eaten raw or cooked and is used for preserves, pies and sauces. The historical bulletin cautions that overcooking can reduce flavor and increase bitterness.[4]