Herbs or lianas [shrubs, rarely trees], deciduous or evergreen, often aromatic. Wood with broad medullary rays. Leaves alternate, simple, petiolate. Leaf blade unlobed, margins entire. Inflorescences terminal or axillary, racemes or solitary flowers, rarely fan-shaped cymes. Flowers bisexual; calyx enlarged, petaloid, usually tubular, [1-,] 3-, [6-, rarely 5-]merous, lobes valvate; corolla usually reduced to scales or absent; stamens 5, 6, or 12 [multiples of 3 or 5], free or adnate to styles and stigmas, forming gynostemium; anthers extrorse; pistil 1, 4-6-carpellate; ovary inferior, partly inferior, or superior; placentation axile (and ovaries 4-6-locular) or parietal; ovules many per locule, anatropous. Fruits capsules [follicles], regularly to irregularly loculicidal, rarely indehiscent [septicidal]. Seeds often flattened; endosperm copious.

Distribution

Primarily pantropical and subtropical.

Discussion

Genera 5, species ca. 600 (3 genera, 28 species in the flora).

Selected References

Duchartre, P. 1864. Aristolochiaceae. In: A. P. de Candolle and A. L. P. de Candolle, eds. 1823-1873. Prodromus Systematis Naturalis Regni Vegetabilis.... 17 vols. Paris etc. Vol. 15, pp. 421-498.

Gregory, M. P. 1956. A phyletic rearrangement of the Aristolochiaceae. Amer. J. Bot. 43: 110-122.

Schmidt, O. C. 1935. Aristolochiaceae. In: H. G. A. Engler et al., eds. 1924+. Die natürlichen Pflanzenfamilien..., ed. 2. 26+ vols. Leipzig and Berlin. Vol. 16b, pp. 202-242.

Solereder, H. 1889b. Beiträge zur vergleichenden Anatomie der Aristolochiaceen. Bot. Jahrb. Syst. 10: 410-523, tables 12-14.

Solereder, H. 1889. Aristolochiaceae. In: H. G. A. Engler and K. Prantl, eds. 1887-1915. Die natürlichen Pflanzenfamilien.... 254 fasc. Leipzig. Fasc. 35[III,1], pp. 264-273.

Lower Taxa

Aristolochia, Asarum, Hexastylis

Illustrations

	Family ⠉	Taxon	Illustrator ⠉
	Aristolochiaceae Aristolochiaceae Aristolochiaceae Aristolochiaceae Aristolochiaceae Aristolochiaceae	Asarum caudatum Hexastylis minor Hexastylis shuttleworthii var. shuttleworthii Asarum hartwegii Asarum canadense Hexastylis arifolia var. arifolia	John Myers John Myers John Myers John Myers John Myers John Myers
	Aristolochiaceae Aristolochiaceae Aristolochiaceae	Aristolochia reticulata Aristolochia erecta Aristolochia macrophylla	John Myers John Myers John Myers

Key

1	Calyx bilaterally symmetric, usually bent or curved; ovary inferior; stems erect, twining, or procumbent.	Aristolochia
1	Calyx radially symmetric, straight; ovary inferior, partly inferior, or superior; stems rhizomatous.	> 2
2	Sepals distinct; anthers each with prominent terminal appendage; styles connate in column; ovary inferior.	Asarum
2	Sepals connate for most of length; anthers without terminal appendages; styles distinct (except sometimes at extreme base); ovary superior or ca. 1/3-inferior.	Hexastylis