Pinus jeffreyi Seeds | Jeffrey Pine
LATIN NAME: Pinus jeffreyi
COMMON NAME: Jeffrey Pine
Plant Profile
The cones are heavy, twelve to twenty four centimetres long, dark purple when young and ripening to pale brown, with thin woody scales whose prickles bend back toward the cone’s axis rather than standing out. The seeds inside are large, ten to twelve millimetres, and carry a wing far longer than the seed itself. A heavy cone crop is one of the mountain’s reliable autumn events.
The species is named for John Jeffrey, the Scottish plant collector who worked the Pacific coast for a Scottish botanical association in the middle of the nineteenth century and sent seed and specimens back to Britain. The pine was separated from ponderosa in the 1850s, and the separation solved a practical mystery: distillers working its range had suffered explosions they could not explain, and the near-pure heptane in the resin was the reason.
Within its range the tree takes the harder ground. It tolerates serpentine soils, which are poor in calcium and rich in heavy metals, and it is often the dominant conifer on such sites even at low altitude; higher up, on thinner and colder soils, it replaces ponderosa pine as the dominant tree. Hybrids with ponderosa and with Coulter pine do occur, though rarely, because the two species shed pollen at different times.
The uses of the species are quiet ones. The wood is sawn like ponderosa pine for building and box material, wildlife takes the seed from the cones, and the crystallised sap has been eaten as a sweet by people in the mountains. As a garden tree it is grown for its bluish needles, its scent and its tolerance of poor, dry, rocky ground on a cold site.
Science & Biotechnology
Break a needle or warm a piece of resin between the fingers and the tree identifies itself: the smell is sweet, buttery and vanilla-like, closer to a bakery than to turpentine. Ponderosa pine in the same situation smells of resin and lemon. The difference is chemical rather than romantic, and it comes from the volatile fraction of the resin, which in this species is unusual in the extreme.
The volatile part of the resin consists almost entirely of n-heptane, a straight-chain seven-carbon alkane, while the resin of other pines is a mixture of terpenes. That single fact explains the scent, the behaviour of the resin in a still, and the odd history of the tree: n-heptane distilled from this species was pure enough to be chosen as the zero point of the octane rating scale for petrol.
Because the volatile fraction is heptane rather than a turpentine mixture, the resin is a poor raw material for turpentine, and the gum trade passed the species by. The wood, by contrast, is much like ponderosa pine and has been cut for the same construction uses. The chemistry of the resin has since been studied by gas chromatography as a straightforward source of a single compound.
Uses & Benefits
The needles are held in bundles of three, twelve to twenty three centimetres long, stout and grey-green rather than bright, and they persist for several seasons, so an old branch is thick with them. The bark on a mature trunk breaks into plates smaller and less fiery than those of ponderosa pine, and the combination of bluish needles and modest plates is the quickest way to sort the two.
Growing from Seed
Pine seed wants a cold, damp period before it will break, so sow in late winter after keeping the seed cool and moist, or sow in autumn and let the weather do the work. Use a gritty mix of two parts coarse sand or fine grit, one part sieved compost and a little peat, sow at about twice the seed’s own depth, and keep the pan cool and open to the air rather than under glass.
Pine seedlings live with mycorrhizal fungi, and a seedbed without them produces short, yellow, sulking plants. Mixing in soil or litter from under a healthy mature pine, or using a commercial inoculant of a pine-associated fungus, gives the roots a partner from the start. Water sparingly, keep the seedlings in full light, and pot them on when they stand five or six centimetres high.
Our Take
My test for a pine seedling is always the same: crush a needle and smell it. With this species the answer is immediate. Learn it against ponderosa pine first, since the two are forever confused, then compare the long-coned sugar pine and the slow, ancient bristlecone pine.
Related Reading
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