A Floral formula is a

notation In linguistics and semiotics, a notation is a system of graphics or symbols, characters and abbreviated expressions, used (for example) in artistic and scientific disciplines to represent technical facts and quantities by convention. Therefore, ...

for representing the structure of particular types of

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

s. Such notations use numbers, letters and various symbols to convey significant information in a compact form. They may represent the floral form of a particular species, or may be generalized to characterize higher

taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

, usually giving ranges of numbers of organs. Floral formulae are one of the two ways of describing flower structure developed during the 19th century, the other being

floral diagram Floral diagram is a graphic representation of flower structure. It shows the number of floral organs, their arrangement and fusion. Different parts of the flower are represented by their respective symbols. Floral diagrams are useful for flower i ...

s. The format of floral formulae differs according to the tastes of particular authors and periods, yet they tend to convey the same information. A floral formula is often used along with a

History

Floral formulae were developed at the beginning of the 19th century. The first authors using them were Cassel (1820) who first devised lists of integers to denote numbers of parts in named whorls; and Martius (1828). Grisebach (1854) used 4-integer series to represent the 4 whorls of floral parts in his textbook to describe characteristics of floral families, stating numbers of different organs separated by commas and highlighting fusion. Sachs (1873) used them together with floral diagrams, he noted their advantage of being composed of "ordinary

typeface A typeface (or font family) is the design of lettering that can include variations in size, weight (e.g. bold), slope (e.g. italic), width (e.g. condensed), and so on. Each of these variations of the typeface is a font. There are list of type ...

Although Eichler widely used floral diagrams in his ''Blüthendiagramme'', he used floral formulae sparingly, mainly for families with simple flowers. Sattler's ''Organogenesis of Flowers'' (1973) takes advantage of floral formulae and diagrams to describe the

ontogeny Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the stu ...

of 50 plant species. Newer books containing formulae include ''Plant Systematics'' by Judd ''et al.'' (2002) and Simpson (2010). Prenner ''et al.'' devised an extension of the existing model to broaden the descriptive capability of the formula and argued that formulae should be included in formal

taxonomic Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

descriptions. Ronse De Craene (2010) partially utilized their way of writing the formulae in his book ''Floral Diagrams''.

Contained information

Organ numbers and fusion

The formula expresses counts of different floral organs;Bracts and bracteoles are not considered parts of the flower itself, yet they may be included in the floral formula these are usually preceded by letters or abbreviations according to the organ type. They are ordered corresponding to the arrangement of the parts of the flower from the outside to the inside: The labels with darker backgrounds are less common. "V" used by Prenner ''et al.'' for the number of ovules per gynoecium is followed by lowercase letter describing the type of

placentation Placentation refers to the formation, type and structure, or arrangement of the placenta. The function of placentation is to transfer nutrients, respiratory gases, and water from maternal tissue to a growing embryo, and in some instances to remov ...

. For

epicalyx This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary o ...

calyculus This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary o ...

, the letter "k" is used. The numbers are inserted after the labels, they may be formatted as sub- or superscript. If an organ is absent, its number is written as "0" or it is omitted, if there are "many" (usually more than 10–12) instances, it can be written as "∞". Whorls of the same organ are separated by "+". Organ counts within a whorl can be separated by ":", for example when part of the whorl is morphologically different. A range can be given if the number is variable, e.g. when the formula summarizes a taxon. :* K₃₊₃ – a calyx with six free sepals, arranged as two separate whorls :* A∞ – many stamens :* P3–12 – perianth from three to twelve petals Groups of organs can be described by writing the number of instances in the group as superscript. : A5² – 5 groups of 2 stamens The formula can also express organ fusion. Fusion of one organ type can be shown by enclosing the number in a circle, fusion of different organs can be represented by

ties TIES may refer to: * TIES, Teacher Institute for Evolutionary Science * TIES, The Interactive Encyclopedia System * TIES, Time Independent Escape Sequence * Theoretical Issues in Ergonomics Science The ''Theoretical Issues in Ergonomics Science' ...

, as e.g. in Judd ''et al.'' Prenner ''et al.'' state that this method is difficult to achieve via standard typesetting. Joining of organs can be more readily written using

parentheses A bracket is either of two tall fore- or back-facing punctuation marks commonly used to isolate a segment of text or data from its surroundings. Typically deployed in symmetric pairs, an individual bracket may be identified as a 'left' or 'r ...

"(…)" if instances of the same organ are fused. Fusion between different organs can be achieved by

square In Euclidean geometry, a square is a regular quadrilateral, which means that it has four equal sides and four equal angles (90-degree angles, π/2 radian angles, or right angles). It can also be defined as a rectangle with two equal-length adj ...

" ��, eventually

curly brackets A bracket is either of two tall fore- or back-facing punctuation marks commonly used to isolate a segment of text or data from its surroundings. Typically deployed in symmetric pairs, an individual bracket may be identified as a 'left' or 'r ...

"". :* A(5) – five fused stamens :* (5) A5– corolla fused from 5 petals, fused to stamens Prenner ''et al.'' propose superscript zero for a lost organ, and superscript "r" for a reduced one. Ronse De Craene uses a

degree symbol The degree symbol or degree sign, , is a typographical symbol that is used, among other things, to represent degrees of arc (e.g. in geographic coordinate systems), hours (in the medical field), degrees of temperature or alcohol proof. The symbo ...

to mark a staminode (infertile stamen) or

pistillode Gynoecium (; ) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) ''pistils' ...

(infertile carpel). :* A3:2^r+5⁰ – (Prenner ''et al.'') androecium in two whorls, first contains 3 stamens and 2 staminodes, second whorl lost :* A1+2° – (Ronse De Craene) androecium in two whorls, first whorl containing a stamen, second whorl containing two stamens in Ovary position Ovary position is shown by alternating the "G" label. Simpson circumvents the intricate formatting by expressing the ovary position by words.

Symmetry

Symmetry Symmetry (from grc, συμμετρία "agreement in dimensions, due proportion, arrangement") in everyday language refers to a sense of harmonious and beautiful proportion and balance. In mathematics, "symmetry" has a more precise definit ...

or arrangement may be described for the whole flower; in such case the corresponding symbol is usually placed at the beginning of the formula. It may be also outlined separately for different organs, placing it after their labels or numbers, or it may not be included in the formula at all. It is described by following symbols:

Sexuality

Sexuality of the flower can be highlighted by ☿ or Male and female sign

for hermaphrodite (bisexual), ♂ for male (staminate) and ♀ for female (pistillate) flower. The symbols are usually placed at the beginning of the formula, after or before the symmetry symbol. Prenner ''et al.'' recommend to use the corresponding symbols (♀ and ♂) only for flowers of separate sexuality. Ronse De Craene utilizes the words "pistillate" or "staminate" instead of the symbols. Floral formula can also incorporate the fruit type, Judd ''et al.'' place it at the very end.

Examples

↯ K3 3 A1°–3°+½:2°Ğ(3) – the formula of ''

Canna indica ''Canna indica'', commonly known as Indian shot, African arrowroot, edible canna, purple arrowroot, Sierra Leone arrowroot, is a plant species in the family Cannaceae. It is native to much of South America, Central America, the West Indies, and ...

''; asymmetric flower; calyx of three free sepals; corolla of three free petals joined with androecium; androecium in two whorls, the outer whorl contains 1–3 staminodes, the inner contains ½ of a stamen and 2 staminodes; gynoecium fused of 3 carpels, inferior ovary B Bt^C K3:(2)^C↓ C3:2^r↓ A(3):2^r↓+4^r:1⁰ 1↓ Vm8–10 – the formula of ''

Tamarindus indica Tamarind (''Tamarindus indica'') is a leguminous tree bearing edible fruit that is probably indigenous to tropical Africa. The genus ''Tamarindus'' is monotypic, meaning that it contains only this species. It belongs to the family Fabaceae. ...

''; bract and petaloid bracteoles; monosymmetric calyx of three and two petaloid sepals; monosymmetric corolla of three and two reduced petals; two whorls of stamens, the outer monosymmetric from three fused and two reduced stamens, the inner of 4 reduced and 1 lost stamen; monosymmetric gynoecium of 1 carpel with superior ovary; marginal placentation with 8–10 ovules per gynoecium.

Using boxes

Notes

References

Bibliography

N S Subrahmanyam, Modern Plant Taxonomy, Vikas Publishing House Pvt Ltd, 2009.

External links

Kvetné vzorce
– a website dedicated to floral formulae (in Slovakian)
Table 2.1. Floral formulae; symbols used in this book. In Ronse De Craene, p. 39

Symbols employed in floral formula. In Subrahmanyam, p. 42Floral Diagram Generator
– a website to generate floral diagrams from floral formulae. {{botany Flowers Plant morphology