PROJECT OUTLINE

HYPOTHESIS

The Lesser Celandine, Ranunculus ficaria, appears to have different flowering habits in sunny and shady conditions (there are fewer flowers produced by plants in the shade). Other variables, leaf length, leaf width, flower pedicel length, leaf petiole length and leaf colour are also affected by the differences in habitat. 

INTRODUCTION

Describe the plant and its preferred conditions, also any reasons fewer flowers need to be produced in shady conditions. Produce a map of the area showing sampling sites. 

EXPERIMENTAL WORK 

Pairs of sites are chosen the only difference between the two one is shaded and the other sunny. Both sites are no more than 100m apart. The shaded sites are well shaded from all aspects by tall trees and shrubs.

Sites chosen:

A & B - Shady/Sunny and dry, undisturbed with long grasses present.

C & D - Shady/Sunny and damp, beside the river, with mainly celandine present.

E & F - Shady/Sunny and dry with mainly celandine present. 

MEASUREMENTS 

100 plants were measured at each site.

On each plant the number of flowers and the number of leaves are counted. Selected flower pedicel length, leaf petiole length, leaf length and leaf width are measured in millimetres. The leaf colour is recorded using a colour chart and the presence of a dark vein noted (Y/N). Light intensities are recorded using a light meter, giving a comparison of light falling on the sample area. 

RESULTS 

A results chart is produced for each site. The means of all measurements are to be calculated and displayed as a series of bar charts. Mean flower number : mean leaf number is used to compare the numbers of flowers in sun and shade. Statistical analysis using z-test for unmatched pairs. Leaf colour/presence of dark stripes analysed using X².    

PROBLEMS 

Ensuring all plants have comparable leaves and flowers removed for measuring. A sampling device will be constructed. Deciding the leaf colour at six different sites. A colour chart will be produced. 

CONCLUSIONS 

“THE INFLUENCE OF SHADING ON FLOWERING AND MORPHOLOGY IN THE LESSER CELANDINE, RANUNCULUS FICARIA.”      

SUMMARY: 

1. The aim of this project is to show that shade living plants of the Lesser celandine differ in their morphology to sun living plants.

2. Results show that there are more flowers produced, at a given time, by plants living in sunny habitats compared to plants in the shade. Flower stem length and leaf stalk length are both longer in shady habitats than sunny habitats. Leaf size does not appear to vary much between the two conditions, but leaves are larger where there is competition from other plants than at sites where celandines grow alone.

3. From the results obtained my conclusion is that the Lesser celandine does produce fewer flowers when growing in shady conditions, also leaf and flower stem lengths are longer in shady habitats compared to sunny habitats and leaf colour varies between the two conditions. Leaf length and width and the proportion of veined to non - veined leaves are not shade related.

INTRODUCTION:

The lesser celandine is a low growing perennial plant. Its rosette of leaves appear around January, and the flowering starts in March. Flowering lasts several weeks before the plants die off around June. Reproduction by bulbils formed at the leaf axils is an alternative to flowering.

From a variety of sources (Fitter, 1987; Aichele, 1975; Clapham, Tutin and Moore, 1987) it appears that the lesser celandine prefers a damp, nutrient rich, non - acidic soil in sun or shade.

Do the plants have two different growth forms, in shady and sunny habitats? This project aims to investigate differences at shaded and sunny sites in flower numbers and morphology.

The hypothesis being tested is that shade living and sun living plants of the lesser celandine show variations in flower production, pedicel and petiole length, leaf length and width, leaf colour and vein presence. These variables were selected because they appeared to differ on an initial inspection of the sunny and shady sites. The six sites sampled have been chosen as pairs, differing only in the amount light present. Sites A (shaded) and B (sunny) were both dry and undisturbed with long grasses present. Sites C (shaded) and D (sunny) were damp, being beside a river, with mainly celandines present. Sites E (shaded) and F (sunny) were both dry with mainly celandines present. All shaded sites had overhanging tree and shrub canopies containing some evergreens. All sunny sites were open with no trees or shrubs casting shade at any time.

Figure 1: Map showing the locations of the six sample sites.

EXPERIMENTAL METHODS:

At each site 100 plants were sampled, from a small area restricted by shade cover or openness. The first plant was selected randomly by dropping a stick with a blue painted end, and taking the plant nearest the blue end as plant 1. The next 99 plants were the nearest neighbours to plant 1.

A leaf selector was made from a circle of card with a segment removed, the segment is chosen by finding a number between 1 and 360 to represent an angle, from South, at the centre of the segment, this ensures the same aspect leaf and flower are measured from each plant.

All sites were sampled within 4 days of each other to allow fair comparisons of flower numbers. 

Figure 2: method used to select the leaf and flower from each plant: 

For each plant the number of flowers and leaves are counted. Using the selector one flower (where present) and one leaf from each plant are removed., as closely to the ground as possible. 

Figure 3: method used to measure the length of pedicels and petioles.

Measurements are made using a ruler in millimetres from the base of the flower or leaf to the bottom of the stem.

Figure 4: method used to measure leaf length and width.

A colour chart was made with a range of leaves to represent the colours: very light (VL), light (L), light/medium (LM) and dark (D). Leaves at different sites were then compared with the leaves on the colour chart. The presence or absence of a dark stripe along the mid-rib of the leaf was also recorded (Y/N). 

Lesser Celandine leaf without a dark mid rib	Lesser Celandine leaf showing the dark mid rib

Light intensity of all sites was measured, using a light meter, within a 20 minute period at a time when there was no cloud, but, because bright sunlight went off the scale readings were taken in the early evening.

RESULTS 

Mean and median values were calculated for all data, shown here as line graphs, which also represent the range of measurements, showing how close the mean and median results were for each measurement.

Chart legend:

The sun and shade relationships for all the morphological factors measured are shown by the graphs below.

Chart Legend:

FLOWERS PRODUCED 

The flower : leaf ratio was used for easy comparison between sites as mean leaf numbers varied slightly. The bar charts for flower to leaf ratio show values of less than 0.05 flowers per leaf at the shaded sites, A, C and E. Values for the sunny sites are between 0.19 and 0.3 flowers per leaf.

Legend for bar graphs:

FLOWER PEDICEL AND LEAF PETIOLE LENGTH 

Several trends are shown by referring to the bar charts below for flower pedicel and leaf petiole lengths. Flower pedicel lengths at shaded sites, A, C and E, have mean values of 220mm, 109mm and 113mm which were longer than the mean values of 144mm, 79mm and 95mm for their comparative sunny sites, B, D and F (i.e. damp compared with damp etc.), confirmed by z-tests for flower pedicel length which showed shady sites had longer pedicels than sunny sites. Leaf petiole length for sites C and D (both damp) was the same, but for shaded sites, A and E, the mean lengths of 167mm and 80mm were longer than for the sunny sites, B and F, at 110mm and 65mm.

Z - TEST RESULTS

FLOWER PEDICELS:

Flowering stems were longer at all shady sites.

LEAF LENGTHS AND WIDTHS:

For both dry sites, shady leaves were longer than sunny leaves.

For the damp sites, shady leaves were longer than sunny leaves.

For the dry site with other plants, shady leaves were wider than sunny leaves.

For the remaining sites there were no differences in leaf widths:

LEAF LENGTHS AND LEAF WIDTHS 

From the graphs of mean values (above) leaves from site A with mean length 28.7mm and mean width 29.2mm are the largest of all shaded sites. Overall site B mean length and width, 24.5mm and 24.7mm are largest for all sunny sites. No trends are apparent from the histograms (below) of leaf length and width means. Z-tests were carried out which showed for dry site shady leaves were longer than sunny leaves, but at damp sites shady leaves were shorter than sunny leaves. At the dry sites with other plants shady leaves were wider than sunny leaves. At the remaining sites widths did not differ significantly. Leaf length to width ratios vary, but without a pattern.

LEAF COLOUR AND VEIN PRESENCE 

Analyzed using X² test. 

For leaf colour a null hypothesis of no difference between leaf colour at shady and sunny sites was formulated. Value of X² calculated as 79.604 which is significant, at 3 degrees of freedom, 5% significance level = 7.815.

LEAF COLOUR RESULTS FROM SIX SITES CONTAINING LESSER CELANDINES.

Code: L = light, LM = Light / Medium, M = Medium, D = Dark.

Chart for X²

X represents:	O = observed	E = expected

Degrees of freedom = 3

For leaf veins a null hypothesis of no difference in proportions of veined and non - veined leaves at shady and sunny sites was formulated. The value of X² calculated as 0.992 is not significant, at 1 degree of freedom, 5% significance level = 3.841

LEAF VEIN RESULTS FROM SIX SITES CONTAINING LESSER CELANDINES.

Chart for X²

X represents:	O = observed	E = expected

Degrees of freedom = 3

COMPARATIVE LIGHT INTENSITIES AT SIX SITES CONTAINING LESSER CELANDINE.

DISCUSSION

This project set out to determine if any of the variables, flowers produced; flower and leaf stem length; leaf length / width; leaf colour or vein presence; differed between shady and sunny sites.

The bar charts of flower : leaf ratios shows clearly that more flowers are produced by plants in sunny habitats than in shade, at a given time. Reproductive effort saved, as celandines can reproduce by bulbils, can be utilised for other functions.

From the bar chart of mean results for flower stem lengths the shaded sites produced longer stems than the comparable sunny sites. This was also true for leaf stem lengths at the dry sites, (A & B and E & F). Mean lengths at the damp sites (C & D) were the same. Additionally both mean petiole and pedicel lengths at the dry sites with competition from grasses, (A & B), are longer than the mean lengths without competition. I had expected leaf stalk lengths to be longer in the shade as plants trying to maximize light interception become etiolated, overall the results showed this. Longer pedicels and petioles would be expected where celandines compete with other species for light. Mean flower stem lengths at all sites are longer than leaf stalk lengths. As this plant is insect pollinated this means the flowers are accessible to the pollinator.

Z - tests show leaf length at dry sites (A & B and E & F) is longest in the shade while at damp sites (C & D) it is shortest in the shade. Additionally, leaves at the shady dry site with competition (A) are wider than at the comparable sunny site (B). I had expected some differences in leaf length and width as shade tolerant species often increase their leaf area when shaded. The main differences were at sites A & B which have the largest leaves. The effects of competition and water availability may be more important than shade or sun, larger leaf size could be beneficial when there is competition.

Analysis of leaf colour produced a value of X² = 79.604, which is greater than the critical value of 7.815 at 5% significance for 3 degrees of freedom. The null hypothesis can be rejected, there is a difference between leaf colours at shaded and sunny sites. Shaded sites have fewer light and dark leaves than expected and sunny sites have more light and dark leaves than expected. Sunny leaves may produce more pigment (chlorophyll) which eventually fades, while shaded leaves produce “average” pigmentation but are not subject to fading. For proportions of veined and non - veined leaves the value of X² was 0.922. This is less than the critical value of 3.841 for 5% significance and one degree of freedom. The null hypothesis of no difference in proportions of veined and non - veined leaves at shaded and sunny sites cannot be rejected. Veined leaves occur in the same proportions at both shaded and sunny habitats.

CRITICISMS

Fewer flowers were recorded at the sites in the shade, as expected, however, the counts were carried out early in the season. Repeating the procedure 2 - 3 weeks later would confirm a trend if fewer flowers are still produced at shady sites.