Seeds in Solanaceae (Full Document)
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Because of the size of the
original document only a part is given. However, reference is made to
the full document which is a pdf file containing full text (including
a key to the plant family based on seed- and embryo morphology) , diagrams
and pictures. Should you wish to obtain the drawings or the pictures,
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Seeds in Solanaceae (Full Document)
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INTRODUCTION
Like in all plants families the taxonomy in Solanaceae is based on a whole set of plant morphological characteristics such as, color and form of the corolla, appearance or lack of hairs, hair types, calyx caracteristics, androecium (anthers), gynoecium, fruits etc..The taxonomic importance of the embryo and cotyledons in seeds of the plant family Solanaceae has been stressed by A.T. Hunziker in his preface of "The Genera of Solanaceae (A.R.G.Gantner Verlag K.G., 2001) and in his key to the subfamilies as well in his detailled descriptions of the 92 genera this features have been highlighted significantly.This page describes the seeds in the Solanaceae with a focus on seed and embryo morphology.
SEEDS IN SOLANACEAE
Seed morphology
A general structure of the seed can be found in diagram 1 and diagram 2.
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Diagram 1: General structure
of a seed
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Diagram 1: General structure
of a seed and embryo
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Click on image to enlarge
1. Seed form
The form (see full document) of the seed in the plant family Solanaceae varies widley and ranges from:
2. Seed size
The size of the seed is mostly between 1.2-2.5 mm. long; sometimes smaller (hardly 0.75 mm. long; between 0.6-1 mm.long; the smallest being 0.3-0.4 mm. long.) or larger (between 4-6.5 mm. long) exceptionally very large: 7-8 mm.long.
3. Episperm/Testa
The surface of the seed (episperm (testa) see full document) might be smooth, minutely pitted, granulate, foveolate, minutely foveolate-reticulate, foveolate-reticulate, finely reticulate, reticulate, reticulate-pitted, reticulate with straight or undulate ridges, muricate-reticulate, reticulate-tuberculate, tuberculate (warty) , tuberculate with transverse striae ,rugose-tuberculate, verrucose, finely honey-combed, honey-combed, alveolate, arcuated ridges with striae between the ridges, furrowed or ridged.
Two outstanding cases are worth mentioning:
4. Endosperm
The oily endosperm in the plant family solanaceae may be scarce, but in general is rather abundant.
5. Embryo form
The solanaceous embryo may be thick or slender, straight, long or short, slightly curved, vermiform, annular, coiled or subcoiled. In Datura the embryo has a peculiar hook or curvature near the apex of the cotyledons (see full document for examples).
6. Cotyledon form
The cotyledons have broad cotyledons in the three genera of the tribe Cestreae, together with Merinthopodium, Markea, and Juanulloa. In all other taxa the width is the same as the rest of the embryo.
7. Relationship between the total embryo size and the cotyledons size.
One can distinguish two cases in the relationship between the total embryo size and and the cotyledons size:
In an exceptional case the two cotyledons are unequal.
8. Cotelydon arrangement.
Cotyledon arrangement ( for examples see full document)is incumbent and sometimes oblique or accumbent and sometimes oblique.
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Cotyledon arrangement
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Size of embryo and cotyledones
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Click on image to enlarge
GLOSSARY (Ref. 946a)
Accumbent: Cotyledon arrangement: Lying along or against another body, e.g. the cotyledons haveing their edges agianst the radicle.
Alveolate:(Seed surface) Pitted, covered with small cavities.
Annular: (Embryo form) Ring-shaped.
Angulate-subreniform:(Seed form). The form is somewhat reniform and the seed is winged.
Bacilliform: (Seed form) Rod-shaped, rod-like.
Boomerang-shaped: (Seed form) In the shape of a boomerang.
Coiled: (Embryo form) Turned, like a spiral.
Compressed: (Seed form) Flattened lenghtwise ,usually lateral
Cotyledons: The embryo leaf or leaves of seed plants that usually stores or absorbs food in a young seedling; in angiosperms (flowering plants) the following distinction is made with respect to the cotyledons: dicots have two cotyledons and monocots have one cotyledon.
Cuboidal-elongated:(Seed form) The form is cubic but lenghtend
Curved:(Embryo form) Bent but smoothly, not abrupt.
Depressed: (Seed form) Flatened from above (vertically) , somewhat sunken at the centre
Discoidal: (Seed form) Discoid, with a rounded blade and thickened margin.
Discoidal-reniform:(Seed form) Between discoidal and reniform.
Elaiosomes: Fruits and seeds (diaspores) of ant-dispersed plants posess elaiosomes - appendages of various shapes - which are attractive for ants. It is known that elaiosomes contain lipids, proteins, sugars and vitamins and thus constitute a valuable nutritional source for ants.
Ellipsoid-ovate(Seed form) Elliptic figure-egg-formed
Elongated: (Seed form) Ellipsoid but lengthend.
Embryo: Young sporophyt, dipoid (2n), result of fertilization. The mature embryo consists of cotyledons (seed leaves), hypocotyl (stem-like embryonic axis below the cotyledons), radicle (embryonic root).
Endosperm: Food storage tissue, triploid (3n), result of fertilization.During seed maturation the endosperm will develop into a storage tissue that will provide nutrients to the seedling as it emerges (in monocots) or that will be digested and stored by the cotyledons before germination (in dicots)
Episperm: The skin or coat of a seed, especially the outer coat; protective outer layer of seeds of flowering plants
Foveolate: (Seed surface) Minutely pitted.
Foveolate-reticulate:(Seed surface) Between minutely pitted and netted.
Globose-depressed: (Seed form) Globose but on one side slightly flattened.
Globose-reniform: (Seed form) Intermediate form between globose and reniform.
Honey-combed: (Favosus)(Seed surface) Excavated in the manner of a section of honeycomb.
Incumbent: Cotyledon arrangement: Folded inwards and lying upon, used of cotyledons having the radicle resting on one side of a cotyledon instead of along the edge.
Imbricate:Seed form Overlapping in regular order, as the scales on a snake.
Javelin-shaped: (Seed form) Long, thin and very narrow, like a spear..
Lenticular: (Seed form) Lens-shaped, resembling a double conves lens.
Oblique: Cotyledons with a slight degree of inaequality of the two sides.
Ovoid: (Seed form) Ovate form resembling an egg.
Peltate: (Seed form) Shield-shaped.
Peripheric: Pertaining to the boundery or outer surface.
Polyedric: (Seed form) Many surfaces and many margins
Prismatic: (Prism-shaped) (Seed form) Having several longitudinal angles and intermediate flat faces.
Proximale pole: Nearest to the axis
Reniform: (Seed form) Kidney-shaped, resembling the figure of a kidney, that is to say crescent-shaped, with the ends rounded.
Reticulate: (Seed surface). Netted, like a network
Reticulate-foveolate:(Seed surface) Between reticulate (like a network, netted.) and foveolate (minutely pitted).
Sphaerical-angular: (Seed form) Forming nearly a true sphere and winged
Straight:(Embryo form) Not curved but erect
Striae:(Seed surface) Fine linear markings, lines, fine grooves.
Subcoiled: (Embryo form) Somewhat coiled.
Subglobose:(Seed form) Somewhat globose
Suborbicular:(Seed form) Somewhat circular.
Subpolyedric: (Seed form) Somewhat like polyedric.
Subsphaerical: (Seed form) Somewhat globose. Almost forming nearly a true sphere.
Testa: (seed coat): Outer protective layer of the seed, developed from the integuments of the ovule, maternal dipoid tissue.
Triqueter: (three-edged) (Seed form) Having three acute angles with concave faces (genraaly used as synonym of trigonus (trhee-cornered).
Tuberculate: (Seed surface) Covered with wart-like projections.
Undulate: (Seed surface) Wavy structure.
Vermiform: (Embryo form) Worm-shaped.
Verrucose:(Seed surface). Warty
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