Chloranthaceae R.Br. ex Sims

Every, J.L.R. (2009). Neotropical Chloranthaceae.

Morphology

Description

Evergreen trees (2-30 m tall) and scandent shrubs, large prop roots regularly present, glabrous or with non- glandular trichomes, all parts strongly aromatic. Leaves simple , opposite, decussate , petiolate , petiolar bases form a cylindric or quadrangular persistent sheath around the stem , nodes swollen; blade fleshy to coriaceous , pinnately veined, margins crenate - serrate ; stipules 4. Staminateinflorescence in dioecious species ( axillary or terminal , 1 to several spikes, axis racemose or paniculate; leaf-like bracts present), in monoecious species (solitary spikes on pistillate inflorescence axis or within a cymules (along with pistillate flowers)). Pistillateinflorescence axillary or terminal , cymules, spikes, racemes or panicles; bracts present. Staminateflowers basic, 60-300 flowers per spike , without perianth , ebracteate, 1-3 sessile stamens, anthers, oblong , longitudinally dehiscent . PistillateFlowers simple , perianth lobes 0.5-3mm, free at the base or partially to completely united forming a small tube, adnate to the ovary ; ovary inferior or semi-inferior, sometimes nude, carpel 1, locule 1, stigma 1 sessile or on very short style . Fruit a drupe , fleshy , aromatic and brightly coloured, exocarps thin, mesocarp fleshy , endocarp hard, or multiple with colourful, juicy floral bracts. Seed 1 per fruit , small, brown or black smooth or minutely papillate, endosperm well developed, oily.

General Description

Notes on delimitation

• Chloranthaceae are probably sister to magnoliids (Moore et al. 2007) as the only family in the order Chloranthales.

Number of genera

• One: Hedyosmum Sw. with 44 species.

General notes

• Hedyosmum brasiliense has medicinal property.
• One species H. mexicanum C. Cordem. provides edible, sweet tasting fruit.
• Hedyosmum is derived from the Greek words hedy (pleasant) osmum (smelling).
• An interesting family from an evolutionary point of view, lending its name to the Chloranthoid Hypothesis, which suggests that the first flowering plants had the similar small, basic, unisexual, wind-pollinated flowers.

Status

Native.

Distribution

Distribution in the Neotropics

• Growing throughout the Neotropics, predominantly in wet, cool, montane forest at altitudes anywhere between 500m and 3,000m.
• Two-thirds of the species are found in Andean South America, primarily in disturbed sites.

Diagnostic

Other important characters

• Prop roots.
• Floral bracts becoming colourful and succulent and appealing to birds.
• Long flowering season.
• Long staminate inflorescences with abundant pollen.

Distinguishing characters (always present)

• Swollen leaf sheath in-between leaf stalks.
• Unisexual flowers.
• Minute perianth.
• Opposite leaves.
• Crenate to serrate leaf margins.
• NB! Pungent odour from all broken parts of the plant.

Key differences from similar families

• Loranthaceae are estipulate.
• Caprifoliaceae have a distinct perianth.
• Piperaceae have alternate leaves.

Literature

Important literature

Maas, P. J. M. & Westra, L. Y. Th. 2005. Neotropical Plant Families. 3rd ed. P. 106. A.R.G. Gantner Verlag K.G., Ruggell.

Moore et al. 2007. Using plastid genome-scale data to resolve enigmatic relationships among basal angiosperms PNAS: 104(49).

Todizia, C. A. 1988. Chloranthaceae: Hedyosmum. Flora Neotropica. Monograph 48. The New York Botanical Garden, New York.