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Cytological Observations on Tripsacum dactyloides

1944; Missouri Botanical Garden; Volume: 31; Issue: 4 Linguagem: Inglês

10.2307/2394366

2162-4372

Edgar Anderson,

Plant tissue culture and regeneration

Taxonomic work on Tripsacum!has indicated that T. dactyloides is a very complex species.It is composed of at least five different entities, one of which grows in an isolated area in western Texas and has been recognized taxonomically as T. dactyloides var.occidentale (loc.cit).Aside from this variety, Т. dactyloides extends from central Texas and northern Kansas eastward to Connecticut and Florida (Map 1).Cytologically, T. dactyloides is a polyploid complex and has some races with 18 pairs of chromosomes and others with 36.The cytological work reported below extends the known range of one diploid race into Missouri and Arkansas and suggests that Т. dactyloides may be exclusively tetraploid along the eastern seaboar Materials and Methods.-At the beginning of the project an earnest attempt was made to cultivate the Mexican and Guatemalan species of Tripsacum along with a comprehensive collection of the various forms of T. dactyloides.After three years of partial success this had to be abandoned as too costly in time and effort.None of these species are winter-hardy in St. Louis, even with careful attention, and even the southern Texas strains of T. dactyloides get gradually weaker, and a few die each winter.As a greenhouse plant Tripsacum does well in St. Louis during the winter, but it is difficult to bring through the long, hot summer.The collection was kept in fair condition for two years by transplanting to the breeding plot every spring and then putting the plants back into the greenhouse in September.However, when they are treated this way they do not have a regular flowering period, and some of them do not flower at all.A project of this sort could be carried out more efficiently at some such experiment station as La Jolla, California, or College Station, Texas, where the exotic species of the genus are easily grown out of doors.Since Tripsacum is a close relative of maize and may even be involved in the history of our cultivated varieties," such a project would seem to be of fundamental importance.From the more northerly part of its range Tripsacum dactyloides was readily grown from seeds or as transplants.Seedlings grew best when planted out of doors and brought in after several weeks of cold weather.Planted out the following spring, they gave good-sized plants by the second summer.In transplanting specimens from the wild, early fall was found to be the most effective time of year and preferable to summer, late fall, or spring.The plants grew well when