and Laboratory Methods. 2689 



Laboratory Outlines for the Elementary Study of Plant 



Structures and Functions from the Standpoint 



of Evolution. 



SUBKINGDOM, ANGIOSPERMAE. 



A number of forms to represent the general evolution of the flower in mono- 

 cotyls and dicotyls, 



LXXVI. Sagittaria latifolia Willd. Arrow-head. 



Class, Monocotyledones. Order, Niadales. Family, Alismaceae. 



The wide-leaved arrow-head grows in moist ground on the margins of ponds, 

 creeks and canals. If fresh material is not available, good herbarium specimens 

 may be used. Flowers and other parts may also be preserved in alcohol. 



Sporophyte. 



1. Sketch and describe the entire plant, noting the character of the leaves, 

 stem, roots, and inflorescence. 



2. Sketch the staminate flower, showing sepals, petals and stamens. How 

 many parts in each set ? 



3. Sketch the carpellate flower and describe the parts present. What parts 

 of the two flowers are cyclic and what parts spiral in arrangement ? Is this 

 sporophyte moncEcious or dioecious ? 



4. Under dissecting microscope draw a sepal, a petal, a stamen (microsporo- 

 phyll) and a carpel (megasporophyll). 



5. Cut cross sections of a young stamen, mount, and draw under low power. 

 How many microsporangia ? Note that the stamen is made up of anther and 

 filament. 



6. Cut off one side of a carpel so as to expose the ovule (megasporangium). 

 Draw under low power, showing the stigma, short style, and ovulary. Note that 

 the stigma is a new organ not present in any of the forms previously studied. 

 Why is the stigma necessary to this carpel ? 



LXXVI I. RaniincHliis abortivns L. Crowfoot. 



Class, Dicotyledones. Order, Ranales. Family, Ranunculaceae. 



This plant is common in April and May along brooks, on hillsides, in mead- 

 ows, and along roads. 



Sporophyte. 



1. Sketch the entire plant, showing the various organs. 



2. Sketch the flower and describe the condition of the four sets of floral 

 organs. Note that the flower is bisporangiate. Compare with the cone of 

 Selaginella. 



3. Draw a sepal, a petal, a stamen, and a carpel under dissecting micro- 

 scope. 



