BOT 360F - Families of Vascular Plants 

Assignment 2

The text below was prepared by a class member for assignment 2 and illustrates many good points that others should keep in mind in doing similar assignments (many other class members turned in work that was similar in quality; this is just one example). I have intercalated comments in boxes like this one. I have also added some in-line corrections or suggestions in boldface Times Roman, and bolded some points that I thought were especially valid.

 

 

 

 

 

 

 

Xyridaceae

The purpose of this paper is to synthesize information on the Xyridaceae [family] collected from web-based and print resources and to provide a comparison between these resources as information sources on families of vascular plants.

This text was originally in two very long paragraphs that I have split up for the sake of easier reading. Obviously this student wanted to fit in a lot of information into the two paragraphs that I suggested using. When not confronted with an articficial constraint like the one I imposed, try to structure your writing in paragraphs that each address a separate topic that you want to cover. Subheadings can often be an additional aid to the reader.

 

 

 

 

 

Members of the Xyridaceae [family] are monocotyledons that are members of the Commelinidae tribe and Commelinales order (Mabberley, 1987). The Xyridaceae or yellow-eyed grass family was first discovered and named in 1823 by Carl Adolf Agardh (Kral, 1983). The Xyridaceae family is composed of perennial or sometimes annual herbs that grow in damp, often saline ecosystems (Kral, 1983). The Xyridaceae family is usually characteristic of wetlands. It is a family that is widespread in tropical and subtropical and warm temperate zones and is diverse in the southeastern United States, tropical America and southern Africa. The Xyridaceae family includes 5 genera, Xyris, Abolboda, Orectanthe, Achlyphila and Aratitiyopea and 300 species (Zomlefer, 1994). The majority of species are found within the genus Xyris which includes 260 species.

The family falls into two groups, Achlyphila and Xyris and Abolboda and Orectanthe. Abolboda and Orectanthe are very closely related, but the affinities between Achlyphila and Xyris are not close. It was originally thought that the genera were distributed among two families, Abolbodaceae and Xyridaceae (Kral, 1992). However, discoveries of morphologies in the Neotropics, including the discovery of the genus Achlyphila as a link between Abolboda and Xyris made the distinction difficult to accept and today the families are considered to be one.

The Xyridaceae is not a very economically important family. A few species of the genus Xyris are cultivated as ornamental plants for pools and aquaria (Zomlefer, 1994). Species of Xyridaceae are often used in different regional locations for medicinal purposes and to make figures for Hindu temples in Java (Mabberley, 1987).

The family is characterized by cormlike stems or occasionally rhizomes and simple, narrow, alternate leaves that usually occur in basal tufts and have parallel venation, sheathing at the base and no stipules. The influorescence is usually indeterminate and forms a conelike head or spike, with spirally arranged bracts. The influorescence is terminal and occurs on a long scape. The flowers are bisexual and are slightly bilateral. The perianth is differentiated into a calyx and corolla, each in the axil of a stiff, papery, leathery bract. Each flower consists of 3 sepals which are distinct and dimorphic. The inner sepal is membranous and wrapped around the corolla and it falls as the flower opens. The 2 lateral sepals are subopposite, stiff, papery and keeled and are persistent. The flowers also have 3 petals which are distinct. The petals form a corolla with a narrow tube and a distinct 3-lobed flaring limb. The flowers are usually ephemeral and yellow or white and they wilt quickly. The flowers have 3 stamens, opposite the petals, usually alternating with 3 staminodes, which are short filaments that are adnate to the petals. The flowers also have 3 carpels, a superior ovary and 3 stigmas. The fruit is usually a loculicidal capsule that is surrounded by the dried corolla tube and clasped by the 2 lateral sepals. The seeds are numerous and minute and are usually longitudinally ridged (Zomlefer, 1994, Fernald, 1950, Hutchinson, 1973, Britton and Brown, 1896). There is a significant amount of information available on the family Xyridaceae and the genera and species found within this family.

There are some differences between the informational content on Xyridaceae obtained using web-based resources and print resources. Most web-based resources describe the characteristics of the Xyridaceae family. In some cases, web-based sites such as Watson and Dallwitz's Delta Database and the Flora of North America Online, describe the characteristics of the Xyridaceae family in as much detail as print resources such as Zomlefer’s section on Xyridaceae. The reason for the similarity between good web-based resources and print resources is that the majority of this web based information is based on or refers to print resources. Most web-based resources on Xyridaceae cite from journal articles by Robert Kral who is an expert on Xyridaceae and its genera and has published numerous articles on the subject. It should be noted that the web-based catalogues are used to find the location of print resources within library systems at the University of Toronto. These resources can therefore be found online as well as in journals or monographs available in the library. In many cases, journal articles are available using internet resources and access to these resources is often restricted to university students. The web-based resources however are accessible to the general public, which makes them easier to obtain and use.

Remember that you now know about a number of print resources that are especially valuable for getting at the older literature. Not only can you check the bibliographies of works like Die Natürlichen Pflanzenfamilien, but you can also make use of indices like Taxonomic Literature II and its predecessors. And don't forget to browse the stacks!

 

 

 

 

It is difficult to access pre-1900 resources including monographs and journal articles. Most web-based information is based on current studies and current information. Journal articles provide details on species characteristics compared to monographs that focus on characteristics that define the Xyridaceae family. It should also be noted that web based resources such as the New York Botanical Garden’s online Index Herbarium provide access to detailed photographs of members of the Xyridaceae family, while print resources such as Robert Kral’s article on genera of the Xyridaceae provide access to detailed illustrations that indicate the features of members of the family.

The photographs available using web-based resources are helpful in providing a visual aid to species of the family, while the illustrations in print resources are helpful in detailing characteristics and minute details of plant anatomy that aid in identification and classification.

I think this is an important point that should make you think about the difference between photographs and illustrations, even ones like your own sketch notes. Do you think you would take in as much from the material you study in lab if you could photograph your dissections? Why or why not?

 

 

 

 

Journal articles provide peer reviewed scientific information on plant families, genera and species, monographs usually contain compilations of information from various sources and web-sites on plant families can range from sites that provide information on the characteristics of plant families to sites that provide details on individual species. Since the latter case is true for both journal articles and monographs as well, it is important to critically evaluate both web-based and print resources in order to find useful information on vascular plant families.

 

The image (below) is meant as a reminder to the class of how incredibly useful Mabberley's Plant Book is in any situation that involves researching genera or families of vascular plants. Click on the image to go to a page where ther are quotes even more over the top in praise of this book.

Literature Search

Ries, Heinrich. 1892. Review of the North American species of the genus Xyris. Bulletin of the Torrey Botanical Club. 19 (2): 35-43.

Search Method

Searched JSTOR for Xyridaceae. Limited the search to articles published between 1800 and 1900. Conducted a search using the University of Toronto library catalogue to determine if the journal was available in the library. Found the article in the Bulletin of the Torrey Botanical Club.

Description of article

The article provides a description of the characteristic features of the genus Xyris and as well as descriptions of species within the genus found in North America. The article provides illustrations of the scales and lateral sepals of 14 species of Xyris which can be used for identification.

Arber, Agnes. 1922. Leaves of the Farinosae. Botanical Gazette. 74 (1): 80-94.

Search Method

Searched JSTOR for Xyridaceae. Limited the search to articles published between 1900 and 1950. Conducted a search using the University of Toronto library catalogue to determine if the journal was available in the library. Found the article in the Botanical Gazette.

Description of article

The article provides information on the leaves of particular species of Xyridaceae, focusing on the genus Xyris.

 

Kral, R. 1983. The Xyridaceae in the Southeastern United States. Journal of the Arnold Arboretum. 64 (3): 421-429.

Search Method

Search by subject. Selected botany. Selected Agricola and Plant Sciences Databases. Searched for Xyridaceae. Searched for an article published between 1950-1990. Selected the first article that met the criteria.

Description of article

The article provides a description of the characteristics of the Xyridaceae family along with information on the genera found within the family, the taxonomic divisions within the family and the economic importance of the family. The article also provides a description specifically of the genus Xyris.

 

Kral, R.B. 1992. A treatment of American Xyridaceae exclusive of Xyris. Annals of the Missouri Botanical Gardens. 79(4) 819-885.

Search method

Searched for Xyridaceae using the Web of Science e-index. Picked an article published after 1990 that appeared in the search. Conducted a search using the University of Toronto library catalogue to determine if the journal was available within the university library system. Found the article in the 1992 edition of the Annals of the Missouri Botanical Gardens.

Description of article

The article describes the taxonomy of the Xyridaceae and the characteristics of the family. The article provides detailed keys to species within each genera as well as hand drawn illustrations of species within each genera.

 

Bridges EL, Orzell SL. 2003. Two new species and a new combination in southeastern United States Xyris (Xyridaceae) from Florida. Novon 13 (1): 16-25.

Search method

Searched for Xyridaceae using the Web of Science e-index. Picked the first article that appeared in the search. Conducted a search using the University of Toronto library catalogue to determine if the journal was available in the library. Found the article in the spring edition of the journal Novon.

Description of article

The article describes two new species of Xyris from peninsular Florida and discusses their ecological, geographical, and taxonomic relationships with other Xyris. The two species are Xyris calcicola, which is found primarily in central and southern Florida in calcareous habitats and Xyris correlliorum, which is endemic to southern Lake Wales Ridge lakes. The article also provides a key provided for all 24 Xyris species in Florida.

 

Britton, N. and Brown, A. 1896. An Illustrated Flora of the Northern United States, Canada and the British Possessions: Volume 1-Ophioglossaceae to Aizoaceae. Charles Scribner’s Sons, New York.

Search Method

Browsed the reference section for monographs published earlier than 1900. Searched for the Xyridaceae family using the index at the back of the book.

Description of monograph

The monograph provides a description of the characteristics of the Xyridaceae family along with information and a detailed key on some species within the genus Xyris that are found in North America.

Fernald, Merrit Lyndon. 1950. Gray’s Manual of Botany. American Book Company, New York.

Search Method

Browsed the reference section for monographs published earlier than 1950. Searched for the Xyridaceae family using the index at the back of the book.

Description of monograph

The entry on Xyridaceae in the monograph provides a description of the characteristics of the Xyridaceae family along with information and a detailed key on some species within the genus Xyris that are found in North America.

 

Mabberley, D.J. 1987. The Plant-Book: A Portable Dictionary of Vascular Plants. Cambridge University Press, New York.

Search Method

Searched for publications by Mabberley using the library catalogue system. Searched for the call number for the monograph entitled The Plant-Book. Searched for the entry on the Xyridaceae family in the book.

Description of monograph

The monograph provides information on the characteristics of the Xyridaceae family along with information on its genera and their economic uses.

 

Kral, R.B. 1994. Xyridaceae. In Flora of the Guianas: Series A, Phenerograms: 182. Gorts-van Rijn (ed). Koeltz Scientific Books, New York.

Search Method

Searched for Xyridaceae using the library catalogue system. Found the call number for the monograph and found the monograph in the library stacks.

Description of monograph

The monograph provides detailed information on the members of the Xyridaceae family found within Guiana and the Guiana Highlands. The monograph provides detailed information and keys on the species within genera of the Xyridaceae family.

Zomlefer, Wendy, B. 1994. Guide to Flowering Plant Families. The University of North Carolina Press, Chapel Hill.

Search Method

Searched for publications by Zomlefer using the library catalogue system. Searched for the call number for the monograph entitled Guide to Flowering Plant Families. Searched for the Xyridaceae family using the index at the end of the book.

Description of monograph

The monograph provides detailed information on the characteristics of the Xyridaceae family. It includes details on the distribution of the family as well as representatives of the family in Canada and the US. It includes details on the economic uses of members of the Xyridaceae family. It also includes notes on the characteristics of species within the family.

 

 

 

 


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