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Annual or perennial herbs, shrubs or trees, sometimes scandent or prostrate; root system fibrous, fleshy or tuberous. Branches dichotomously or trichotomously forked, often swollen at nodes, sometimes armed with, and climbing by means of, thick, straight to recurved, axillary spines. Leaves alternate, opposite, subopposite or whorled, simple; sessile or petiolate; exstipulate; blade membranaceous to carneous, often marked and coarsened with conspicuous raphides, symmetric or oblique at base, margin usually entire, sometimes toothed or lobed, glabrous or pubescent; pinnately veined. Inflorescence of terminal or axillary, diffuse or congested, paniculate or corymbose cymes (sometimes flowers axillary and solitary, or in thyrses, racemes, spikes, umbels or capitules), pedunculate, usually bracteate or variously involucrate; involucre, when present, of free or connate segments, often calyx-like, enclosing 1 or many flowers, persistent or deciduous, often accrescent around fruit, green or brightly coloured. Flowers regular or nearly so, bisexual or unisexual, then sometimes sexes with different perianth, usually dioecious when flowers unisexual; perianth plicate or contorted in bud, green or coloured, campanulate, funnel-shaped, or tubular, sometimes urceolate or salver-shaped, connate completely to a truncate tube or for more than 2/3 with a 3-5-dentate or -lobed limb, upper part mostly caducous after anthesis, tube persistent in fruit, usually accrescent, indurate at base and forming an anthocarp; stamens 1-10(-30), hypogynous, included or exserted, filaments unequal, filiform, free or united at base in small, often swollen collar, presumably functioning as nectary, anthers dehiscent by longitudinal slits, 4-locular, 2-locular when mature, dorsifixed or basifixed; pistil 1, included in perianth, ovary superior, 1-carpellate, 1-locular, sessile or stipitate, ovule 1, anatropous or campylotropous, style short or elongate, sometimes absent, stigma simple, capitate, peltate, penicillate or fimbriate, terminal, rarely lateral or style stigmatic along one side. Fruit a 1-seeded anthocarp, formed by persistent, coriaceous, fleshy perianth-tube or its indurated base with enclosed achene or utricle; anthocarp costate (5- to 10-ribbed at base), sulcate or winged, glabrous or pubescent, often viscous when wet; seed 1, testa hyaline, endosperm scanty, perisperm abundant, usually mealy or fleshy, embryo curved or straight.


Guianas present, tropical America present
About 400 species in 31 genera, mostly in tropical America, with a few temperate representatives; in the Guianas 14 species in 6 genera, including the cultivated Bougainvillea and Mirabilis.


The family can easily be recognised by some anatomical features, in particular abnormal secondary growth by the included phloem, is easily spotted with a hand lens (). See also Metcalfe & Chalk 1983, p. 211; Carlquist 1988, p. 256; Lindeman et al. 1963, p. 249). In the wood of Guapira, Neea and Pisonia, phloem is found as islands that abaxially accompany short, irregular radial rows or chains of small to medium-sized vessels. These conspicuous structures, formed by vessels, parenchyma strands and abaxial phloem islands are diffusely spread throughout the wood. The rays, consisting of procumbent to square cells, are narrow, uniseriate with accidentally low, biseriate parts.
In the wood of Guapira, Neea and Pisonia, the nyctaginaceous genera indigenous in the Guianas, some variation between the studied species was found in the size and number of woodanatomical characters, i.e. the size of the phloem islands, the vessel diameter, the height of the rays, and the amount of fibre pits (see remarks in the family description). It is, however, not possible to distinguish between these genera.
The family description is based on wood samples of Guapira, Neea and Pisonia.
Although Bougainvillea is not indigenous for the Guianas, it is very often found as ornamental plant. Bougainvillea is deviating in several aspects. The phloem islands, typical for the other Nyctaginaceae, are here also found. They are, however, arranged in tangential zones, at the adaxial side of continuous, 4-6 cells wide parenchyma bands (, ). Towards the bark, each parenchyma bands is bounded by a zone without vessels.
In Bougainvillea the rays are high, slightly irregular, mostly up to 4 cells wide, often with long uniseriate margins, consisting of upright and some rows of square cells. Many ray cells are of appr. the same height as the vessel members and parenchyma cells and contribute to the ripple marks ().>

Taxonomic changes

A lectotype is selected for Pisonia glabra (taxonomical synonym of Guapira eggersiana).


Included phloem present as islands of 500/600 x 375/550 μm, islands oval (to round), rarely kidney-shaped, diffusely spread (, ). Often raphids or styloids included ().
Vessels at the adaxial side of the phloem islands, as irregular or regular radial rows and chains up to 8 vessels long, intermingled with few parenchyma strands (); 1-3(-5) vessel groups per mm² (5-10 vessels per mm²); vessels round to oval, diameter 50-100(-150) μm. Perforations simple. Intervascular pits alternate, round to slightly oval, 4-6 μm. Vessel-ray pits similar to intervascular pits or slightly larger. Vessel member length ca. 150-200 μm.
Rays uniseriate up to 14-18 cells, 350-500 μm high, consisting of procumbent to nearly square cells, with scanty biseriate parts of 1-4 cells high (), 7-12 per mm.
Parenchyma as fusiform cells and strands of 2 cells (), ca. 150 μm high; paratracheal as scanty cells in the vessel groups, apotracheal as one cell wide layers, abaxially accompanying the phloem islands.
Fibres thin- to thick-walled, walls ca. 3-6(-8) μm, lumen (6-)18-20 μm wide. Pits simple, slit-like, the occurrence on both radial and tangential walls varying from scanty to numerous.
Ripple marks present to absent in Guapira, formed by fibres, parenchyma and vessels members, rarely also by rays (); very vague to absent in Neea and Pisonia.
Remarks: The vessel diameter is up to 50 μm in Neea mollis () and in the Guianan material of N. spruceana. The vessel diameter of the Krukoff collections of N. spruceana from Brazil however, is (50-)85-90(-115) µm.
In some species (i.e. Guapira eggersiana) only square ray cells were observed. The rays of Pisonia macranthocarpa are deviating by their height: (1000-1200 μm; up to 40 cells) with biseriate parts of up to 6 cells; these rays are terminally or laterally accompanied by upright cells ().
Short irregular, narrow apotracheal bands of parenchyma intermingled with thinwalled fibres are present in Guapira eggersiana. Diffuse apotracheal parenchyma is abundant in Pisonia macranthocarpa in short, one cell wide bands; fusiform cells are also found as ray margins or “sheath cells”.


BotanicalThe woods of the two genera Guapira and Neea are similar and treated together.
TreeSmall to medium-sized trees. Only Guapira kanukuensis reported as large tree.
Description of the woodNo distinction between sapwood and heartwood, pale yellow, whitish to grey. Texture very coarse, the included phloem islands seeming as large vessels on longitudinal sections. Grain straight. Luster low.
WeightGenerally 600-800 kg/m3 (G. eggersiana, N. floribunda and most of unidentified nyctagineous wood samples), but 480-600 kg/m3 in G. cuspidata and N. spruceana, or up to 1000 kg/m3 in G. salicifolia and N. ovalifolia.
UsesAny use reported and no commercial possibilities (Record & Hess 1943, p. 410).


Since specimens of 3. Guapira and 5. Neea are sometimes difficult to separate, a combined key covering Guianan species of both genera is provided below, as well as a key to the species within each genus which is located in the respective generic treatments