Didymelaceae

Disclaimer

Content is from Kirkbride et al. 2006Kirkbride et al. 2006:
Kirkbride JH, Jr, Gunn CR, and Dallwitz MJ. 2006. Family guide for fruits and seeds, vers. 1.0. Accessed September 2020-January 2022. URL:  https://nt.ars-grin.gov/seedsfruits/keys/frsdfam/index.cfm ., without modification. 
Updates are forthcoming.

Taxonomy

Didymelaceae J. Leandri

Common name: Didymeles Family.

Number of genera: 1 genus.

Number of species (Mabberley 1997): 2 species.

Disseminule

Fruit (intact or entire).

Description

Fruits: Pistil(s) compound; 1; 1-pistillate; with carpels united. Fruit pericarpium; simple; drupedrupe:
(indehiscent drupe) a fleshy, indehiscent fruit with one more hard pits enclosing seeds, derived from single, superior, simple or compound ovary; (dehiscent drupe) a fruit with a dry or fibrous to fleshy or leathery outer husk that early to tardily breaks apart (or opens), exposing one or more nutlike pits enclosing the seeds
; without persistent central column; not within accessory organ(s); 1-seeded; 1-seeded; 3.5 cm long; with 1-carpellate; sulcatesulcate:
surface relief—having one or more elongate, relatively narrow and shallow depressions or grooves
; with 1-sulcate; in transection tereteterete:
approximately circular in cross section; width and thickness approximately equal
; apexapex:
the point farthest from the point of attachment, or the "tip" of an organ
not beaked; indehiscentindehiscent:
not opening on its own, as in a fruit
. Epicarpepicarp:
outer layer of fruit wall or pericarp, if divided into layers; note here used synonymously with exocarp
durable; glabrousglabrous:
without hairs
; without armature; smooth, or not smooth; without wing(s); without apicalapical:
at or pertaining to the end of the seed or fruit distal from its point of attachment (i.e., base)
respiratory hole. Mesocarpmesocarp:
the middle layer of the pericarp, if divided into layers
present; fleshy; composed of 1 unified layer; without lactiform cavity system; & endocarpendocarp:
the inner layer of the pericarp, if divided into layers
sharply differentiated. Endocarpendocarp:
the inner layer of the pericarp, if divided into layers
present; not separating from exocarpexocarp:
outer layer of fruit wall or pericarp, if divided into layers; note here used synonymously with epicarp
; bonybony:
very hard and rather brittle, like bone
; not splitting into 1-seeded pyrenes; stone unilocular; stone 1-loculate; without wing; without operculumoperculum:
a dehiscent cap (or lid) of a seed or fruit that opens during germination or dehiscence
; without secretory cavities; without mechanism for seedling escape; without grooves; without longitudinallongitudinal:
of or relating to length or the lengthwise dimension
ridges. Funiculusfuniculus:
(alt. funicle) stalk connecting the ovule (later seed) to the ovary (later fruit) placenta
short; short without seed bearing hookswith hooks:
bristles or spines with curved or backwards pointing tips, or with secondary bristles along their length
(retinacula); not persisting in fruit after seed shed.

Seeds: Arilaril:
(broad sense) appendicular structure that wholly or partly envelops a seed and is produced from or a modification of the funicle, raphe, or outer integument; usually fleshy or pulpy, sometimes spongy or tufted-capillate, often brightly colored
absent. Seed larger than minute; not bowl shaped; not nutlike; without winglike beakbeak:
a usually firm, terminal appendage, sometimes tapered
; without caudatecaudate:
tapering to a long, tail-like appendage
appendage(s); at maturity without food reserves; without canavanine. Sarcotestasarcotesta:
pulpy or fleshy outer layer of the seed coat, simulates aril
absent. Testatesta:
seed coat
present; without markedly different marginalmarginal:
at, on, or close to the margin or border
tissue; without fleshy or leatheryleathery:
texture—moderately thick, tough, and very pliable
layer over hard layer; tight (assumed); surface unsmooth; surface with merged raised features; surface reticulatereticulate:
surface relief—netted, raised walls or concave grooves forming a net-like surface pattern with flat, concave, or convex interspaces
; 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; glabrousglabrous:
without hairs
; without wings; without collar; without operculumoperculum:
a dehiscent cap (or lid) of a seed or fruit that opens during germination or dehiscence
; colored; monochrome; not becoming mucilaginousmucilaginous:
resembling mucilage; moist and sticky
when wetted; surrounding embryo. Embryo differentiated from food reserve; well developed; 1 per seed; completely filling testatesta:
seed coat
(no food reserve); at one end of seed not extending into a depression or cup; foliatefoliate:
appearing leaf-like
; with investinginvesting:
(of embryo) embryo is nearly or completely filling seed coat, straight, and axile and centric with spatulate cotyledons and covering the stalk for at least half its length; (of cotyledons) cotyledons spatulate and covering the stalk for at least half its length
cotyledons; straight; with cotyledons abruptly connected to hypocotyl-radicle; without coleorhiza; without simmondsin; without stomata; not green; with 2 or more cotyledons. Cotyledons 2; well developed; 1 times length of embryo; somewhat to significantly wider than hypocotyl-radicle; 10 times wider than hypocotyl-radicle; entirely concealing hypocotyl-radicle; foliaceous; massive; flat; smooth; with apicesapex:
the point farthest from the point of attachment, or the "tip" of an organ
entire; with margins separate, or connate (with age); basally entire; equal in size; not punctatepunctate:
surface relief—dotted with pits or with translucent, sunken glands or with colored dots, similar to pitted
dotted. Hypocotyl-radicle small; straight; not thickened.

Distribution

General distribution: Old World.

Detailed distribution: Africa (Madagascar).

References

Literature specific to this family: Sutton, D.A. 1989a. 15. The Didymelales: A systematic review. In: P.R. Crane & S. Blackmore, eds., Evolution, Systematics, and Fossil History of the Hamamelidae, vol. I: Introduction and 'Lower' Hamamelidae, pp. 279–284. Clarendon Press, Oxford.

General references: Cronquist, A. 1981. An integrated system of classification of flowering plants, 1,262 p. Columbia University Press, New York, 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, and Spjut, R.W. 1994. A systematic treatment of fruit types. Mem. New York Bot. Gard. 70:1–182.