Iteaceae J.Agardh

Milliken, W., Klitgard, B. and Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://creativecommons.org/licenses/by/3.0

Morphology General Habit

Shrubs, much branched, to 4 m tall

Morphology Leaves

Leaves crowded at ends of branches, alternate, spiraling, simple, shortly petiolate, lamina elliptical to almost circular, margins finely glandular (hydathodes), dentate / serrate, coriaceous, glossy adaxially, abaxially pubescent with simple, conical or peltate hairs, venation pinnate, pocket domatia present in angles of lateral veins with  midrib; stipules small, deciduous

Morphology Reproductive morphology Inflorescences

Inflorescence (sub) terminal, few-flowered cymes or corymbs

Morphology Reproductive morphology Flowers

Flowers actinomorphic, showy, bisexual, epigynous, 5- merous; calyx tubular, 5 triangular lobes, valvate, erect, pubescent, adnate to ovary, persistent; petals free, imbricate, reflexed, pubescent, clawed, persistent; stamens 5, filaments broad, dentate below  apex, opposite sepals; filaments broad, toothed near  apex, anthers dorsifixed, dehiscing longitudinally; staminodes 5 lacking anthers, narrower than stamens, alternating with stamens and opposite petals; ovary inferior, 2-5 carpels, syncarpous, 5-locular, ovules 4-6 per locule; style 1, stigmas 5, radiating from centre, short

Morphology Reproductive morphology Fruits

Fruit a septicidal woody capsule, 5 valved, crowned by persistent sepals and petals

Morphology Reproductive morphology Seeds

Seeds few, elongate, with cartilaginous testa, reduced at either end.

Note

Notes on delimitation: Placed in the Saxifragales as sister to the non-Neotropical Iteaceae (APG2, 2003). Formerly associated with the Escalloniaceae and Hydrangeaceae. Included in the Grossulariaceae by Cronquist (1981). Number of genera: One genus: Pterostemon S. Schauer  2 spp. (P. mexicanus S. Schauer; P. rotundiflourus Ramírez). Glandular hairs secrete resin which gives the top of the leaf a glossy finish.

Distribution

Central and Southern Mexico. Arid hilly regions. Particularly prevalent on limestone and chalk, elevation 1400-2650 m. Endemic.

Diagnostic

Distinguishing characters (always present): Shrubs. Alternate leaves. Actinomorphic, 5-merous flowers. Tubular calyx. Free petals. Stamens opposite the sepals. Staminodes present. Woody, capsular fruit with persistentperianth parts. Pocket domatia present. Water glands present (hydathodes). Stipules (falling). Scented flowers, white to pink. Key differences from similar families: The following families may be confused with Pterostemonaceae, but differ in the characters listed below: Escalloniaceae: Exstipulate. Racemose or paniculate inflorescence. Flowers with nectariferous disc. Staminodes lacking. Grossulariaceae: Lobed leaf blades with palmatevenation. Racemose inflorescence. Flowers bracteate and sessile. Fruit a berry. Hydrangeaceae: Leaves opposite. Iteaceae: Petals not imbricate. 1 stamen whorl (no staminodes). Bilocularovary. Subinferior-superiorovary. Distributed outside the Neotropics. Rosaceae: Nectariferous disc. Imbricate sepals. Perigynous fruits.