Floral diagram
Floral diagram of Anagallis arvensis.[1]: 307 The dot represents the main axis, green structure below is the subtending bract. Calyx (green arcs) consists of five free sepals; corolla (red arcs) consists of five fused petals. Antepetalous stamens are joined to petals by hairy filaments. Ovary is superior, placentation is free central and the ovules are atropous. |
A floral diagram is a graphic representation of the structure of a
They are typically used with the floral formula of that flower to study its morphology.
History
In the 19th century, two contrasting methods of describing the flower were introduced: the textual
Basic characteristics and significance
A floral diagram is a schematic cross-section through a young flower.[1] It may be also defined as “projection of the flower perpendicular to its axis”.[3] It usually shows the number of floral parts,[Note 2] their sizes, relative positions and fusion. Different organs are represented by distinguishable symbols, which may be uniform for one organ type, or may reflect concrete morphology. The diagram may also include symbols that don’t represent physical structures, but carry additional information (e.g. symmetry plane orientation).
There is no agreement on how floral diagrams should be drawn, it depends on the author whether it is just a rough representation, or whether structural details of the flower are included.
Diagrams can describe the ontogeny of flowers, or can show evolutionary relationships. They can be generalized to show the typical floral structure of a taxon.[1]: 37 It is also possible to represent (partial) inflorescences by diagrams.
A substantial amount of information may be included in a good diagram. It can be useful for flower identification or comparison between
Orientation
Diagrams are usually depicted with the subtending
Symbols used in diagrams
Not only the information contained within diagrams, but also their appearance commonly varies between authors. Some publications include an overview of symbols used.
Bracts and bracteoles, axes
Bracts and bracteoles are commonly shown as
Ronse De Craene | Eichler |
---|---|
inconsistent |
The axis relative to the flower is shown as black circle in Floral Diagrams. When inflorescence is depicted, the position of its main stem is illustrated by a crossed circle. Eichler’s depiction of axes alternates between diagrams.
Ronse De Craene | Eichler | |
---|---|---|
axis relative to the flower | inconsistent | |
main stem of an inflorescence |
Perianth
Perianth parts are also shown as arcs. They may be colored according to their type. In Blüthendiagramme the tepals are usually white with black stroke, sepals are hatched and petals are black. Ronse De Craene implies that it may be sometimes impossible to classify the organs, he shows green perianth parts as black and pigmented as white. Estivation can be accurately shown in the diagram.
Ronse De Craene | Eichler |
---|---|
for sepals or sepaloid tepals | for tepals |
Androecium
Stamens are represented by a cross-section through anthers. In case there are many stamens in the flower, they can be simplified and drawn as circles. Staminodes have a small black circle inside or are painted black in Floral Diagrams, Eichler also fills them black.
Ronse De Craene | Eichler | ||
---|---|---|---|
stamen | or | ||
staminode | or |
Gynoecium
The
Ronse De Craene | Eichler | |
---|---|---|
superior ovary | ||
inferior ovary | ||
half-inferior ovary |
Nectaries
In Floral Diagrams, nectaries are filled by grey color, Eichler fills them by hatching.
Other
Fusion can be shown in diagrams by full connecting lines between organs. Lost organs can be represented by a star (✶), lost perianth parts or bracts/bracteoles can be shown with dashed stroke. It is possible to show the direction of monosymmetry by a large arrow. Resupination may be illustrated by a curved arrow. Floral parts can be accompanied by numbers to show their sequence of initialization.
Floral diagrams and floral formulae
Each of these two concepts is better in expressing some information. Floral diagrams can show the size and relative position of the organs. On the other hand, floral formulae are capable of broader generalization. Prenner et al. view them as complementary methods and state they make an “identikit” flower when utilized together.[2]: 248 Ronse De Craene also approves of their combined use.[1]: xiii
Examples
Partial inflorescence of Theobroma cacao (after Ronse De Craene). Floral formula: ✶ K5 C5 A(5°+5²) G(5) |
Floral diagram of Pyrus communis (after Eichler). Floral formula: ✶ K(5) C5 A10+5+5 Ğ(4) |
See also
- Floral formulae
- Flower
- Floral organs
- Dicot flower
- Monocot flower
- inflorescence
Notes
References
- ^ a b c d e f g
Ronse De Craene, Louis P. (2010-02-04). Floral Diagrams: An Aid to Understanding Flower Morphology and Evolution. Cambridge: Cambridge University Press. ISBN 978-0-521-49346-8.
- ^ ISSN 0040-0262. Archived from the originalon 2018-03-29. Retrieved 2014-11-10.
- ^ a b Eichler, August Wilhelm (1875). Blüthendiagramme, erster Theil: Enthaltend Einleitung, Gymnospermen, Monocotylen und sympetale Dicotylen. Leipzig: Wilhelm Engelmann.
- ^ Eichler, August Wilhelm (1878). Blüthendiagramme, zweiter Theil: Enthaltend die apetalen und choripetalen Dicotylen. Leipzig: Wilhelm Engelmann.
- ^ Schaffner 1916.
- ^ Church, Arthur Harry (1908). Types of floral mechanism; a selection of diagrams and descriptions of common flowers arranged as an introduction to the systematic study of angiosperms. Oxford: Clarendon Press.
- ^
Sattler, Rolf (1973). Organogenesis of flowers; a photographic text-atlas. Toronto, Buffalo: University of Toronto Press. ISBN 0-8020-1864-5.
- ^
Stützel, Thomas (2006). Botanische Bestimmungsübungen: Praktische Einführung in die Pflanzenbestimmung (2nd ed.). Stuttgart (Hohenheim): UTB, Stuttgart. ISBN 9783825282202.
- ^
Simpson, Michael George (2010). Plant Systematics. Oxford (Great Britain): Academic Press. ISBN 978-0-12-374380-0.
- ^
Weberling, Focko (1992). Morphology of Flowers and Inflorescences. Cambridge: Cambridge University Press. ISBN 9780521438322.
Bibliography
- Schaffner, John Henry (June 1916). "A General System of Floral Diagrams" (PDF). Ohio Journal of Science. 16 (8): 360–366. ISSN 0030-0950.