Juglandaceae

Disclaimer

Content is from Kirkbride et al. 2006, without modification. 
Updates are forthcoming.

Taxonomy

Juglandaceae A. P. de Candolle ex Perlab

Common name: Walnut Family.

Number of genera: 8 genera.

Number of species (Mabberley 1997): 59 species.

Disseminule

Fruit (dehisced), or fruit (intact or entire), or seed.

Description

Fruits: Pistil(s) 1; 1-pistillate. Fruit anthocarp; simple; Engelhardia pseudosamara, or pseudodrupe (Juglans Spjut Fig. 44A-B), or tryma (Carya Spjut Fig. 52A-B) & 3 families: Arecaceae, Juglandaceae, Thymelaeaceae); without persistent central column; with styles(s); at apex; within accessory organ(s), or not within accessory organ(s); within involucre (bracts); accrescent; persistent; 1-seeded; 1-seeded; with 2(–3)-carpellate; with carpels united; with carpels remaining united at maturity; with carpels remaining connected at style; without sterile carpels; not sulcate; in transection terete, or flat, or compressed; apex not beaked; indehiscent, or dehiscent. Dehiscent unit "fruit" (Carya). Dehiscent without replum. Epicarp black, or brown (all shades), or green; dull, or shiny; durable; hard; glabrous, or not glabrous (with hairs) (hispid Alfaroa); hairs not glandular; without armature; smooth, or not smooth; ridged, or rugose; without wing(s), or with wing(s); 1–2–3-winged; with wing(s) apical, or encompassing (Cyclocarpa); without apical respiratory hole. Mesocarp present; fleshy; composed of 1 unified layer; without lactiform cavity system. Endocarp present; not separating from exocarp; thin; not splitting into 1-seeded pyrenes; not smooth; with ridges; without wing; without operculum; without secretory cavities; without grooves; with longitudinal ridges, or without longitudinal ridges; without fracturing longitudinal ridges. Funiculus short; short without seed bearing hooks (retinacula); not persisting in fruit after seed shed.

Seeds: Aril absent. Seed larger than minute; cerebriform; not bowl shaped; not nutlike; without winglike beak; without caudate appendage(s); at maturity without food reserves, or without apparent food reserves, or with food reserves; with endosperm; without canavanine. Sarcotesta absent. Testa present; without markedly different marginal tissue; without fleshy or leathery layer over hard layer; tight; dull; surface unsmooth, or smooth; surface with merged raised features; surface sculptured, or veined; without crease or line separating cotyledons from hypocotyl-radicle; without notch along margin where cotyledons from hypocotyl-radicle tip approach each other; without glands; without bristles; glabrous; without wings; without collar; without operculum; colored; monochrome; brown (all shades); thin; not becoming mucilaginous when wetted; surrounding embryo. Hilum punctate (assumed). Endosperm development nuclear; trace (single layer for Carya & Juglans); without fatty acid containing cyclopropene; without apical lobes; without chlorophyll; without isodiametric faceted surface; without odor. Embryo differentiated from food reserve; well developed; 1 per seed; completely filling testa (no food reserve); at one end of seed not extending into a depression or cup; foliate; with investing cotyledons; straight; parallel to seed length; with cotyledons abruptly connected to hypocotyl-radicle; without coleorhiza; without simmondsin; with cotyledons containing oils; without stomata; not green; with 2 or more cotyledons. Cotyledons 2; well developed; not divaricate; 0.75–1 times length of embryo; somewhat to significantly wider than hypocotyl-radicle; unknown, but in some cases quite large; partially concealing hypocotyl-radicle (at least); massive, or thin; much contorted, or crumpled, or once-folded (at least the apices in Engelhardtia & Pterocarya); sculptured; with apices 4- lobed; with margins separate; basally cordate; equal in size; not punctate dotted. Hypocotyl-radicle small; straight; not thickened. Plumule well developed; composed of 2 seed-leaves.

Distribution

General distribution: Pantemperate and pansubtropical (northern hemisphere). New World and Old World.

Detailed distribution: North America, Middle America, South America, Europe, Asia Major, and Oceania.

Notes

Mabberley: "Fruit nut or samara, or drupelike (tryma), the soft husk (involucre) slipping to release the bony pericarp, seed". Do all genera have fruits within involucre bracts?

References

Literature specific to this family: Stone. D.E. 1989. Biology and evolution of temperate and tropical Juglandaceae. In: P.R Crane & S. Blackmore, eds., Evolution, systematics, and fossil history of the Hamamelidae. Vol. 2: 'Higher' Hamamelidae. Syst. Assoc. Special Vol. 40B, pp.117–145. Clarendon Press, Oxford.

General references: Corner, E.J.H. 1976. The seeds of Dicots, esp. vol. 2. Cambridge University Press, New York, Cronquist, A. 1981. An integrated system of classification of flowering plants, 1,262 p. Columbia University Press, New York, Gaertner, J. 1788–1805. De fructibus et seminibus plantarum. The Author, Stuttgart, Goldberg, A. 1986 (dicots) & 1989 (monocots). Classification, evolution, and phylogeny of the familes of Dicotyledons. Smithsonian Contr. Bot. 58 for dicots (314 pp.) & 71 for monocots (74 pp.). [Goldberg's illustrations are reproduced from older publications and these should be consulted], Gunn, C.R., J.H. Wiersema, C.A. Ritchie, & J.H. Kirkbride, Jr. 1992 & amendments. Families and genera of Spermatophytes recognized by the Agricultural Research Service. Techn. Bull. U.S.D.A. 1796:1–500, Mabberley, D.J. 1987. The plant-book, 706 p. Cambridge University Press, Cambridge, Schopmeyer, C.S. 1974. Seeds of Woody plants in the United States. Agric. Handb. 450:1–883, Spjut, R.W. 1994. A systematic treatment of fruit types. Mem. New York Bot. Gard. 70:1–182, and Wood, C.E., Jr. 1974. A student's atlas of flowering plants: Some dicotyledons of eastern North America, 120 pp. Harper & Row, New York.