Picramniales Doweld, Tent. Syst. Plant. Vasc.: xxxviii. 23 Dec 2001; Picramniineae Shipunov in A. Shipunov et J. L. Reveal in Phytotaxa 16: 64. 4 Feb 2011

Distribution Florida, Mexico, Central America, the Bahamas, the West Indies, tropical South America, Bolivia to northern Argentina.

Habit Dioecious, usually evergreen trees or shrubs. Bark often very bitter. Stem in Picramnia magnifolia usually hollow and inhabited by ants of prey.

Vegetative anatomy Phellogen ab initio superficial. Vessel elements with simple perforation plates; lateral pits alternate, usually bordered (sometimes simple) pits. Imperforate tracheary xylem elements fibre tracheids with simple or bordered pits, septate or non-septate (in Alvaradoa often also vasicentric tracheids). Wood rays uniseriate or multiseriate, heterocellular. Axial parenchyma absent or very rare (in Alvaradoa apotracheal diffuse, or paratracheal vasicentric). Sieve tube plastids? Nodes in Picramnia often 1:≥3, unilacunar, with three or more leaf traces. Heartwood in Alvaradoa with resinous? substances. Calciumoxalate present as druses, styloids, and prismatic crystals.

Trichomes Hairs unicellular, simple, with golden yellow content; glandular hairs present on leaves.

Leaves Alternate (spiral), imparipinnate (leaflets usually alternate), with conduplicate ptyxis. Stipules and leaf sheath absent. Petiole vascular bundles? Venation pinnate, brochidodromous. Stomata anomocytic. Cuticular wax crystalloids? Extrafloral nectaries present on lamina. Epidermis with or without mucilaginous idioblasts. Mesophyll with or without sclerenchymatous idioblasts containing calciumoxalate as druses and prismatic crystals and in Alvaradoa styloids. Simple eglandular and glandular hairs present. Leaflet margins serrate.

Inflorescence Terminal or axillary, usually pendant (rarely upright), raceme-like, thyrsoid or botryoid.

Flowers Actinomorphic, small. Hypogyny. Sepals three to five (or six), with imbricate or valvate aestivation, usually connate at base (rarely free), sometimes persistent. Petals three to five (or six), with imbricate aestivation, free (usually absent in male flowers of Alvaradoa). Nectaries usually present (often staminodial; absent in Nothotalisia). Disc intrastaminal, angular (in female flowers of Nothotalisia absent).

Androecium Stamens three to five (or six), in one whorl, haplostemonous, alternisepalous, antepetalous. Filaments free from each other and from tepals. Anthers basifixed or dorsifixed, non-versatile, tetrasporangiate, usually introrse (in Nothotalisia extrorse), longicidal (dehiscing by longitudinal slits); connective in Nothotalisia elongated. Tapetum secretory? Female flowers in Alvaradoa with antesepalous nectariferous? staminodia.

Pollen grains Microsporogenesis simultaneous. Pollen grains tricolpor(oid)ate, shed as monads, bicellular at dispersal. Exine tectate or semitectate, with columellate infratectum, microperforate to microreticulate, echinate (Alvaradoa subovata).

Gynoecium Pistil composed of usually two or three (in Nothotalisia sometimes four) connate carpels (two out of three carpels sterile in Alvaradoa). Ovary superior, unilocular to trilocular (rarely quadrilocular). Androgynophore present in Nothotalisia. Stylodia two or three, short, recurved and pointed, or absent. Stigma bifid or trifid (rarely quadrifid), type? Male flowers often with minute pistillodium.

Ovules Placentation basal to axile (Alvaradoa) or apical (Picramnia), or axile to basal (Alvaradoa). Ovules two per carpel or two per ovary, hemianatropous or anatropous?, ascending and apotropous (Alvaradoa) or pendulous and epitropous (Picramnia), bitegmic, crassinucellar. Micropyle endostomal (bistomal?). Outer integument ? cell layers thick. Inner integument ? cell layers thick. Hypostase present. Megagametophyte monosporous, Polygonum type. Endosperm development ab initio nuclear. Endosperm haustorium chalazal. Embryogenesis onagrad.

Fruit A berry or berry-like fruit (Nothotalisia, Picramnia) or a samaroid capsule (capsule-like samara, Alvaradoa) with persistent calyx and stylodia.

Seeds Aril absent. Seed coat in Picramnia approx. six cell layers thick. Testa vascularized, unlignified or two subepidermal layers lignified and inner layers crushed. Exotesta in Alvaradoa resinous. Endotesta? Endotegmen in Alvaradoa as resinous membrane. Tegmen? Perisperm not developed. Endosperm copious (Picramnia) or absent (Alvaradoa). Embryo straight (or curved?), in Picramnia minute, chlorophyll? Cotyledons in Alvaradoa two, large. Germination?

Phytochemistry Insufficiently known. Leaves with acetate-mevalonate-derived anthraquinones (Alvaradoa), possibly unique bitter anthracenones (anthrocene derivatives linked to C₅-saccharides), possibly unique tariric acid (C₁₈–acetylenic acids) and petroselinic acid (in seed oils); bark with betulinic acid and similar triterpenes, quassinoids present in Picramnia.

Systematics Picramnia (50–60; Florida, Central America, the West Indies, tropical South America), Nothotalisia (3; N. cancellata, N. peruviana, N. piranii; Panamá, northwestern South America), Alvaradoa (1–2; A. amorphoides: Florida, Mexico, Central America, the Bahamas, the West Indies, Bolivia to northern Argentina; A. jamaicensis: Jamaica).

Picramniaceae are sister-group to Sapindanae.

The sister-group relationships inside Picramniaceae are unresolved. However, Picramnia and Nothotalisia share several morphological features not present in Alvaradoa.

Gumillea has been placed as synonym to Picramnia. This is a questionable decision, since G. auriculata differs from Picramnia in several important features, i.a. the ovaries having multiovular locules (eleven ovules/seeds from the bilocular ovary). Gumillea auriculata is known only from a single specimen collected in Peru at the end of the 18^th century (information from APG II site on internet).

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PICRAMNIACEAE (Benth. et J. D. Hooker) Fernando et Quinn