| # The Families of Angiosperms |

L. Watson and M.J. Dallwitz

### Achatocarpaceae Heimerl.

~ Phytolaccaceae.

Habit and leaf form. Small trees, or shrubs (the branchlets sometimes spiny). Plants non-succulent. Leptocaul. Leaves alternate; spiral; non-sheathing; simple. Lamina entire; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire.

Leaf anatomy. The mesophyll containing crystals. The crystals druses and solitary-prismatic.

Axial (stem, wood) anatomy. Internal phloem absent. Secondary thickening developing from a conventional cambial ring.

The vessel end-walls simple. ‘Included’ phloem absent.

Reproductive type, pollination. Unisexual flowers present. Plants dioecious. Female flowers without staminodes. Gynoecium of male flowers absent.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in cymes, or in racemes, or in fascicles, or in panicles. The ultimate inflorescence units cymose. Inflorescences small, branched cymes, racemes, panicles or fascicles. Flowers bracteate; small. Free hypanthium absent.

Perianth sepaline; 4, or 5; 1 whorled; green. Calyx 4, or 5; 1 whorled; polysepalous; regular; persistent; imbricate.

Androecium in male flowers, 10–20. Androecial members free of the perianth; coherent (basally connate); 1 adelphous. Androecium exclusively of fertile stamens. Stamens 10–20. Anthers basifixed (elongate-oblong); non-versatile; dehiscing via longitudinal slits; extrorse. Pollen grains aperturate (the apertures poorly defined, irregular in shape and distribution); 4–7 aperturate; foraminate, or rugate, or colpate (Phaulothamnus); spinulose.

Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled. Gynoecium syncarpous; synovarious (the styles simple, divergent, uncinate); superior. Ovary 1 locular. Gynoecium stylate. Styles 2. Stigmas 2. Placentation basal. Ovules in the single cavity 1; funicled; ascending; non-arillate; campylotropous.

Fruit fleshy; indehiscent; a berry. Dispersal unit the fruit. Fruit 1 seeded. Seeds (strictly) non-endospermic. Perisperm present (copious, mealy). Embryo well differentiated. Cotyledons 2. Embryo curved.

Physiology, phytochemistry. Betalains absent. Ellagic acid absent. Sieve-tube plastids P-type; type III (a).

Geography, cytology. Sub-tropical to tropical. Warm America.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Caryophylliflorae; Caryophyllales. Cronquist’s Subclass Caryophyllidae; Caryophyllales. APG III core angiosperms; core eudicot; Superorder Caryophyllanae. APG IV Order Caryophyllales.

Species 10. Genera 2; Achatocarpus, Phaulothamnus.

General remarks. Seemingly clearly distinguishable from Phytolaccaceae (q.v.) only by the unilocular ovary, though the compiled data (relying on restricted sampling) have them differing also in the absence of betalains.

Illustrations. • Achatocarpus mollis: Das Pflanzenreich 39 (1909). • Achatocarpus gracilis: Das Pflanzenreich 39 (1909). • Phaulothamnus spinescens: Das Pflanzenreich 39 (1909). • Floral diagrams of Achatocarpus and Phaulothamnus (Das Pflanzenreich 39 (1909). • Le Maout and Decaisne: Achatocarpus.

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 8th June 2026. delta-intkey.com’.

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