floral formula

floral formula

an expression giving the information set out in the FLORAL DIAGRAM. For example, a buttercup has the formula K5 C5 A∞g∞ indicating five sepals in the calyx (K), five petals in the corolla (C), and the androecium (A) and gynoecium (g) of an indefinite number of stamens and carpels. g indicates a superior GYNOECIUM. If a number is in brackets this indicates that the parts are fused together.
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The couture collection relied heavily on floral motifs, but the most interesting pieces were those that deviated from that delicate floral formula. For example, a white cocktail dress had a subtle pattern of abstract stones embroidered into the sheer chiffon.
First, when keying out a plant it is most efficient to fully observe a flower's structure, prepare a floral formula, and then progress to keying out.
Even allowing for these differences, it is relatively easy to decipher most of the botanical information contained within a floral formula, no matter what the format is.
The Virtual Floral Formula is a Web site that lets students practice their floral structure interpretation skills using detailed dissection photographs of the flowers of 12 species.
After the opening page (Figure 2), which shows some of the floral diversity of the Australian Proteaceae (but with little or no variation in floral formulae), users progress to a page where they can choose between (1) learning about flower structure and floral formulae in general, (2) learning how to use the Virtual Floral Formula site, and (3) constructing their own floral formulae.
At this stage the images are mostly unlabeled, but in a very small number of cases some information is supplied that cannot be ascertained from the images but is needed to construct the floral formula. Below the image window is the "backbone" of the floral formula (i.e., K C A G: calyx, corolla, androecium, and gynoecium, respectively), along with 13 drop-down menus (Figure 4).
The Virtual Floral Formula allows them to review this material in the days immediately after the practical session and in the period just before the exam.
I have photographed dissection sequences for several species other than those shown in the Virtual Floral Formula. I show these as occasional PowerPoint presentations in lectures and ask the students to write down the floral formula.
In theory exams, as opposed to practical exams, I will often either provide a written description of a flower and ask students to write the appropriate floral formula or, more frequently, provide a floral formula and ask the students to describe the flower.
As best as I can tell, there is nothing available for plants that is even remotely similar to the Virtual Floral Formula, either on the Web or commercially.
The first image is always the floral formula for the family, which is supported by various close-up images of flowers and dissections of flowers.
The Virtual Floral Formula application overcomes many of these limitations by allowing students to progressively assemble a floral formula based on their interpretation of a series of high-quality dissection images.