Wk 7: Flowers and Terrariums

Overview for today:

I. Flower Dissections -

See detailed instructions within folder "Flower Dissections"

Overview below:

1. Purchase flowers (lilies are recommended)

2. Take photographs of flower and flower parts that you label during dissections

3. Upload photos with descriptions on Padlet (5 points)

II. Observe terrariums -

See detailed instructions within the folder "Terrarium activities and assignments"

Overview below:

1. Post a photo of both terrariums side-by-side on the linked Padlet. Indicate the condition of each type of plant in each dish. (1 point)

2. In a separate assignment called 'Questions about terrariums' you will submit your answers about true mosses, spikemosses, and liverworts.(3 points).

Flower dissections

Live flower dissection instructions

Provided supplies

scalpel (look in the Lab 8 bag)
hand lens

Supplies you provide

A live flower. You may choose, subject to the following restrictions: i. make sure the flower is large enough that you can see floral parts without a microscope. ii. Avoid anything in the aster/composite family, which includes anything that looks like a daisy, dandelion, sunflower (see link of examples of asters here), or anything that looks like an peace-lily (they are not really lilies - example of peace lily linked here). "Flowers" in these groups are actually groups of dozens of small flowers packed together. Also avoid irises and orchids because the flowers do not follow typical patterns. Great choices are Lilies or Alstroemeria (Peruvian lily) that can be found at most supermarkets (see them below the flowers to avoid).

Flowers to avoid

Members of the aster/composite family:(avoid)

[insert image of composite inflorescence here]

Peace-lilies and similar flowers: (avoid)

[insert image of arum-type inflorescence here]

Orchids: (avoid)

[insert image of orchid inflorescence here]

Irises (avoid)

[insert image of iris here]

***Use these flowers that are easy and work well: true lilies, Peruvian lilies (aka -Alstroemeria spp.) in last photo below, are easy to find in most supermarkets and very affordable.

[Insert image of lilies and Peruvian lilies (Alstroemeria) here.

Directions

1. Photograph the intact flower before you start dissecting it. (include a sticker)

Note that the sepals and petals may look similar. Each circle of parts in a flower is called a 'whorl'. The outer whorl comprises the sepals and the inner whorl comprises the petals. When sepals and petals look very similar, the term tepals may be used for both of them.

The flower shown below has sepals (outside) and petals (inside) that are similar enough to call tepals.

[insert image of flower with tepals here]

2. Remove the sepals & keep them in separate piles. Count them. If the flower is older, they may pull off easily. Otherwise, carefully cut them off with a razor.

3. Take a photograph with at least one sepal and petal clearly displayed. Label the sepals and petals (add labels on paper prior to photographing (easiest), or on Snapchat, Instagram, Powerpoint or a drawing program afterwards). Use zooming and cropping, such that your photo is close-up and detailed.

4. Remove & count the stamens. Remember that stamen are the pollen producing structures, including a filament and anther, as shown at right:

[insert image of stamen here]

5. Use your hand-lens to examine an anther to determine its phenological stage (its stage in development). If it is not yet opened, it will appear to have 4 closed sacs, with a relatively smooth outer covering. If it has dehisced (opened), the walls of each sac will have reflexed to expose the large pollen grains, which will give the anthers a rough appearance. A time lapse video showing anther dehiscence is found in this link. Rub an anther against a sheet of paper to confirm whether it is dehisced. If it is, the pollen should create a smear. If it has not yet opened, no pollen smear will be evident.

6. Photograph one or more stamens and label the filament and anther. Use the zoom function so the anthers look large and clear. Indicate the total number of stamen on the flower, and the anther’s phenological stage in your description of the photograph on Padlet. Also, in your description indicate where the along the anther the filament attaches - (at the top, bottom, midway, etc).

7. The pistil should still be attached to the base of the flower. Examine the stigma with your hand-lens and determine how many lobes it has (this will be easier to discern on an older flower). Carefully cut longitudinally (long ways) from the base of the style downward to the flower’s pedicel. Open the base along this cut and find the location of ovules - this is the ovary. Note how may ovules there are (one, few, dozens, hundreds, etc.) and describe their arrangement (are they in lines, a big clump, around the center of the ovary or around the outside, etc.?). They may be so tiny that you can only see them with your hand-lens (from the tree lab), and they may be further down towards the flower's pedicel than you would expect. A dissected carpel is shown here:

[insert image of dissected pistil here]

8. Using the cut flower, photograph and label the following structures: stigma, style, ovary, receptacle (which is the flower's base) and pedicel (flower stem). Include a sticker in the photograph. A hypanthium is a cup-like structure to which the anthers and petals attach on some flowers (most flowers do not have this). An example flower with a hypanthium is pictured here:

[insert image of dissected flower with hypanthium here]

When the hypanthium is present, the ovary sits either inside or below it. If your flower has a hypanthium, label it. In your label for this photograph, record the approximate number and arrangement of ovules (are they in long lines, or arranged like a star, or just jumbled together, etc.?).

9. Upload your labeled flower photographs to Padlet (linked here). You should have 4 photographs in total. Find your Padlet column and upload all of your photographs in the same column beneath your name with descriptions. Be sure to follow the Template provided on Padlet in the first column.

Note to Instructors:

Include a scalpel and hand lens as part of the equipment students receive at the start of the semester.
I ask students to submit this assignment over Padlet. I set up the Padlet as a column, with each student's name the header of a column. I then ask them to submit their photographs in a specified order with text boxes for required information. This allows them to compare their results with those of their classmates, and high-quality work from peers can be an example to which other students can aspire. See an example of a Padlet from this assignment here.
I send students a set of stickers at the start of the semester in their equipment box (each student has their own sticker). I require that their photographs include the sticker so I know they are not using dissection images from classmates or the web.

Terrarium Updates

In Week 7, we ask students to update their terrarium Padlet and answer questions about their terrariums.

Assignment Instructions

Open the attached document with questions about the true moss, spikemoss (a lycophyte) and liverwort growing in your terrariums. Add your answers to the document, then save the document to your computer. Use "Browse My Computer" within the rectangular dotted line to find and attach your document. Submit the assignment.

Observations of bryophytes and lycophytes in your terrariums

Your terrariums should have 3 types of plants: a liverwort, a true moss, and a spike-moss which, despite its name, is actually a lycophyte.

Observe & answer the following questions about the liverwort:

1. Is it a thalloid liverwort or a leafy liverwort?

2. Are their rhizoids present? If so, are they growing from the vental (bottom) or dorsal (upper) side? If necessary, gently lift up one portion of the liverwort to make this determination.

3. Are the liverwort individuals sporophytes or gametophytes, and would they make spores or gametes if they reproduced sexually?

Observe & answer the following questions about the true mosses (but not the spike-moss, which is a lycophyte):

1. Are the true mosses in your terrariums gametophytes or sporophytes?

2. Considering your answer to the previous question, are they haploid (with one set of chromosomes per cell) or diploid (with two sets of chromosomes per cell)?

3. Based on what you know about mosses, do these individuals have rhizoids or true roots?

Observe & answer the following questions about the spike-moss (which is a lycophtye)

1. Are the spike-mosses (which are lycophytes) in your terrarium gametophytes or sporophytes? (Consider which is dominant for lycophytes.)

2. Considering your answer to the previous question, are the individuals in the terrarium haploid or diploid?

3. Are the individuals capable of making gametes or spores?

4. Observe a bit of the spike-moss closely with your hand-lens and describe the shapes of the leaves. How many different general leaf shapes do you observe? Describe the shape(s), as well as where each is located along the stem. Having these different leaf shapes is a characteristic of the spike-moss group, but does not occur in all lycophyte species.

Compare the true mosses to the lycophyte spike-moss

1. Which has longer stems? Use the background information about the two groups to explain why this difference occurs. (Note that we are growing a small spike-moss in our terrariums because it is easy to maintain in a small space; other species of lycophyte are larger).