Pittosporum glabratum Seeds | Glabrous Pittosporum
LATIN NAME: Pittosporum glabratum
COMMON NAME: Glabrous Pittosporum
Plant Profile
The fruit is a rounded capsule that turns from green to orange, then splits into two thick, leathery valves like a small mussel shell. Inside, the seeds lie embedded in a viscous pulp that holds them until a bird or a shower of rain works them loose. The coating is a resinous secretion of the capsule’s inner surface rather than a fleshy fruit wall, and it glues the seed to bark and to rock. Seed stored wet will clump, and seed left in the pulp will mould.
Pittosporum glabratum is a shrub or small evergreen tree with alternate, obovate leaves that crowd the tips of the branchlets. The lamina is thick, smooth and quietly glossy above, and the epithet refers to exactly that: glabratus means made hairless, which separates this species from the hairy-leaved pittosporums of the same hills.
Flowering runs through spring on short terminal clusters of small, creamy-white flowers. Each flower carries five narrow, clawed petals and ten stamens set alternately with them, the obdiplostemonous arrangement that marks the family. The capsule then takes most of the summer to swell, and its valves part only when it is fully ripe.
Scent is strongest in the still, warm hours of late morning and carries a surprising distance from a plant in full flower. Small bees, hoverflies and pollen beetles work the clusters.
Science & Biotechnology
Across the genus, phytochemical surveys keep returning two families of compounds: oleanane-type triterpenoid saponins and flavonol glycosides. The saponins are why a leaf extract froths when shaken, and the resinous seed pulp holds a related terpenoid fraction. The chemistry is better characterised than its pharmacology.
Named pittosporums are raised from cuttings: a semi-ripe nodal cutting with the lower leaves stripped, set in a free-draining mix under mist with gentle bottom heat. Tissue-culture work follows the same route at a smaller scale, with nodes surface-sterilised, established on full-strength Murashige and Skoog medium with benzyladenine, and the shoots rooted after an auxin dip. Micropropagation is used mainly to bulk up a selected hedge clone.
Molecular work in the carrot order moved the family decisively. Sequence data place Pittosporaceae as sister to the rest of the Apiales, which includes the carrot family and the aralia family, rather than tucked inside either of them. Within the genus the Chinese species are frustratingly alike in leaf, and identification leans on capsule size, valve thickness and seed number.
Uses & Benefits
This is a hedging plant before it is anything else. The habit is dense and upright, the dark foliage holds its colour through winter, and the shoots regenerate from old wood, which is what makes a tight formal line possible. Clip twice in a season: once after flowering to tidy the spent clusters, once in late summer to true up the face.
Where winters bite, the same plant works as a tub specimen under glass, flowering best with a cool, bright winter and a long warm summer. Keep it out of a dry, overheated room so the scent can accumulate.
In a mixed planting it does the job the hill thickets gave it naturally: evergreen cover at the edge of woodland, shelter for small birds, and early nectar before the summer flowers arrive. It also shrugs off salt-laden wind better than most broadleaved evergreens.
Growing from Seed
Take seed from a capsule that has split of its own accord, and rub the sticky pulp away in dry sand before sowing, because the resin will hold moisture against the coat and rot it in the pan. Sow shallowly, 3 to 5 mm, on a mix of equal parts peat-free compost, coarse grit and sieved leaf mould, and keep it just damp. A cold frame over winter suits fresh seed collected late in the season.
Lift the seedlings as soon as the second true leaf has opened, pot them singly, and grow them on in a bright, frost-free place for their first winter. Plant out at 20 to 30 cm and water through the establishment season, spacing a hedge line at 45 to 60 cm so the plants close into a solid face. Young plants need frost protection for two winters.
Our Take
My own hedge came from a single capsule picked off a hillside shrub, and it has been the least demanding thing in the garden since. If you want the same evergreen scented screen from another genus, the Japanese pittosporum is the well-tried congener and behaves almost identically under the shears, while sweet olive gives you fragrance from the same clipped form. For a darker, slower hedge in the same warm-climate planting, try the Japanese camellia. Clean the pulp off the seed the day you collect it, keep the shears sharp, and expect the same twice-yearly cut.
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