FLOWERS 41 



When a flower has each circle of parts, as the sepals, petals, stamens, and 

 pistils made up of a certain number of divisions, or wnon they appear in multi- 

 ples of that number, the flower is said to be symmetricat. Here we see a 

 very striking example of symmetry in a flower. 



The chief attraction to insects is the nectar which is formed in nectar 

 glands at the base inside the slender tubular corolla. Information is given 

 to the insects of the contents by a faint, sweet odor. This flower is not 

 visited by many day-flying insects. Can you determine the names of any 

 that do come by day? At night the flower opens more widely and the 

 scent becomes much more noticeable. Moths are its chief night visitors. 

 The long proboscis is thrust into the flower and quickly withdrawn, but 

 usually a little pollen is carried off on the palps, to be left on the next flower 

 visited. 



Try to determine what other insects, if any, visit the evening primrose at 

 night. 



Draw a single flower spHt open lengthwise to show the position of the 

 parts, and especially any adaptations to insect pollination. Look for any 

 special means for the prevention of self-pollination. Label all the parts. 



Butter and Eggs (Linaria linaria). — From July to October this very 

 abundant weed may be found especially along roadsides and in sunny fields. 

 The flower cluster forms a tall and conspicuous spike. Can you see any 

 advantages to a plant in bearing its flowers in clusters? 



Describe the general shape of the flowers. The corolla projects into a 

 spur on the lower side ; an upper two-parted lip shuts down upon a lower 

 three-parted lip. The four stamens are in pairs. What is peculiar in their 

 position and structure? Notice the position of the pistil. Could self- 

 pollination easily occur? (The stamens of two lengths may allow self- 

 pollination in stormy weather, when insects fail to reach the flower.) 



Notice that certain parts of the corolla are more brightly colored than 

 the rest of the flower. This color is a guide to insects. How might it help 

 them in this flower ? 



Push a pencil between the two lips of the flower. Does the pencil touch 

 the stamens ? If a bee pushes aside the lips, would it be likely to take any 

 pollen from the stamens ? Do you think other insects than bees would be 

 likely to aid the flower in pollination ? 



Draw the flower from the side, cut lengthwise to show the position of 

 stamens and pistil. Make this drawing diagrammatic. 



Moth Mullein {Verbascum hlattaria). — The moth mullein is one of the 

 most beautiful weeds, despite the fact that few blossoms are found at 

 any given time. The plant flourishes on dry waste land, roadsides, and open 

 fields. It was introduced into this country and has since become common 

 here and in Canada. 



The flowers are found in a long, loose raceme. A raceme is like a spike, 

 except that each flower has its own flower stalk developed. Has this 

 cluster yellow or white flowers ? Into how many parts is the calyx divided ? 

 The corolla? Is the corolla perfectly regular? Notice the five stamens; 

 is there anything peculiar about the filaments? Are they all of the same 

 length ? In spite of the fact that the flower is called moth mullein, it is not pol- 

 linated to any extent by moths. Bees and flies are the chief pollen bearers. 

 Bees which alight on this flower do so for the purpose of collecting pollen. 

 This they usuaUy gather from the short stamens while they cling to the 

 longer ones. As the bee lights on another flower, the pollen on the under side 

 of the body is transferred to the stigma of this flower. 



Draw the flower from above, twice natural size. 



Jewel Weed {Impatiens biflora). — One of the most prevalent of all our 



