|
|
Family guide for fruits and seeds |
The 36 general references listed in character 336, ‘General references’, were examined for each family. Any fruit and seed data encountered were recorded, and those general references utilized were scored in character 336. In addition, references pertaining principally to just one or a few families were examined and any fruit and seed data encountered were recorded, and the specialized references were listed in character 335, ‘Literature’. All references utilized are also listed in the ‘References’ that is accessible via the ‘Introduction’ button on the main toolbar.
Authenticated fruit and seed samples in the USDA, ARS U.S. National Seed Herbarium (BARC), Beltsville, Maryland, were selected that exhibited the range of morphological characters within each family. They were used to collect supplemental data and to prepare illustrations. Samples were documented either by voucher herbarium specimens held in the institution of origin or by specimens deposited in BARC. Additional fruit and seed samples, many identified by comparison, were used to augment the survey of each family.
Fruit and seed topography was observed at 10 to 30 magnifications, using a dissecting stereoscopic microscope equipped with an ocular micrometer. Recorded observations were made at 10 magnifications, except as noted.
In preparing seeds for dissection, mature seeds of representative size and shape were pierced with a small electric drill. The testa was penetrated one or more times, depending on seed size, in areas removed from the embryonic axis. Drilled seeds were placed in a softening solution of 74 percent-distilled water, 25 percent methyl alcohol, and 1 percent dioctyl sodium sulfosuccinate (aerosol OT). They were kept in the solution for one-half to 24 hours, depending on the consistency of the testa. The seeds were sectioned longitudinally by hand. The testa, embryos, and cotyledons were drawn with the aid of a camera lucida fitted on a stereoscopic microscope. Illumination was provided by an above-stage fiber optic system, which split the light into one beam for the microscope and one for the camera lucida. Drawings were prepared first in pencil. They were either traced in India ink on Dupont Cronaflex U-C Tracing Film and scanned to produce image files or scanned to produce image files and then ‘traced’ in Adobe PhotoShop, ver. 7. If there were no suitable seeds in BARC for dissection, then seed and embryo illustrations from 19th Century publications were scanned.
BARC fruits and seeds 1 mm or greater in length were photographed with a Nikon Coolpix 4300 camera. BARC fruits and seeds less than 1 mm in length were photographed using a Nikon SMV 1500 dissecting stereoscopic microscope equipped with a Nikon DXM 1200 digital camera. The images were captured in both systems at the highest resolution possible. The images were edited using Adobe PhotoShop, ver. 7, and saved in the proper format for use via the Internet.
All data were recorded and maintained in DELTA format (Dallwitz, 1980; Dallwitz et al., 1993, 1999) using the DELTA Editor (Dallwitz, 1980; Dallwitz et al., 1999). DELTA format is a free form, unlimited data-coding format, which accepts multistate, numeric, and text characters and provides for linking of image files to both characters and taxa. The DELTA Editor is a user-friendly program for input and maintenance of data in DELTA format and provides easy access to the capabilities of the DELTA software system (Dallwitz, 1980; Dallwitz et al., 1999) developed by Michael J. Dallwitz formerly with the Division of Entomology, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Canberra, Australia. The final character list had 333 characters, which included 17 cone characters, 123 fruit characters, 175 seed characters, and three distribution characters. The illustrative materials, drawings, photographs, and SEMs, were individually scanned. The images were assembled into files using Adobe PhotoShop, and attached to the database. Finally, the database and its ancillary materials were converted to binary format for online access via the Internet using the Intkey program (Dallwitz, 1980; Dallwitz et al., 1993, 1995, 2000).
The noxious weed taxa of the USA were determined by using Internet sources. Three main nationwide sources were consulted first: USDA Agricultural Marketing Service (2006), National Plant Board (2006), and Tasker (2006). Searches were run to locate all documents dealing with noxious weeds in the USA. They were all checked for listings of noxious weeds, especially state documents.
The Association of Official Seed Analysts (AOSA) has a Uniform classification of weed and crop seeds (Lionakis & Wiersema, 1999), and the International Seed Testing Association (ISTA) has its List of Stabilized Plant Names (Wiersema, 2005). Wiersema (2006a, 2006b) has incorporated both lists into the USDA, ARS, National Genetic Resources Program, Germplasm Resources Information Network (GRIN) taxonomy module (www.ars-grin.gov/cgi-bin/npgs/html/index.pl) and is maintaining them. The two lists were extracted from GRIN in April 2006, and the names associated with their appropriate families.