Botany Blog Plants of the Northeastern U.S.

May 10, 2010


Filed under: North American Native Plants — admin @ 23:34

Many years ago I developed a fascination with cold-hardy cacti. There are several Opuntia spp. (Prickly Pears) that naturally occur in the Midwest and one in the Northeastern U.S. (Opuntia humifusa).

Spinystar (Coryphantha vivipara) is quite different and only occurs as far east as Minnesota. It has bright magenta flowers and a single, cylindric stem. This species can be grown in the Northeast but may develop rot near the base if it is allowed to get too wet, particularly during cold weather. This is probably what naturally limits its range to the west.


May 6, 2010

Large White Trillium

Filed under: North American Native Plants — admin @ 00:38

The spring ephemerals are really brightening up the woods now. We are fortunate in central NY to have many calcareous woodlands boasting large populations of large white trillium (Trillium grandiflorum).


All trilliums are protected in New York State because they are considered exploitably vulnerable.  Plants are considered to be exploitably vulnerable when they are “likely to become threatened in the near future throughout all or a significant portion of their ranges within the state if causal factors continue unchecked” (NYCRR §193.3). While it may seem unnecessary to protect a plant that can be locally abundant, this and other trilliums are often lacking in forests with a history of disturbance, particularly forests that have established on formerly cultivated land.


New York State Register and Official Compilation of Codes, Rules and Regulations of the State of New York (NYCRR)


May 3, 2010

Perigynous flowers

Filed under: Uncategorized — admin @ 22:16

Flowers can be characterized based on the position of the ovary in relation to the other parts of the flower. When the floral parts arise from a position below the ovary, the flower is said to be hypogynous (hypo=below; gynous=female) and the ovary superior since it is above the point where the other floral parts are inserted. When the floral parts arise from a position above the ovary, the flower is said to be epigynous (epi=above) and the ovary inferior since it is below where the other floral parts are inserted.

There is another, special case of an inferior ovary where the bottom of the sepals, petals, and stamens are fused into a cup around the ovary called a hypanthium, or floral cup. Such a flower is termed perigynous (peri=around), because the hypanthium surrounds the ovary. The presence of a hypanthium is a characteristic feature of some families of plants, particularly the Rosaceae and Grossulariaceae. I had a few minutes to kill today and decided to dissect a hyacinth flower that was in the lab and to my surprise found that Hyacinthus orientalis also has a perigynous flower. Here is a closeup of an entire flower

Common Hyacinth

Flower cut in half longitudinally (below)

Perigynous flower

One last image after the ovary was removed so that the insertion of the stamens at the top of the hypanthium is more clearly visible. Also note the drop of nectar near the base of one of the filaments.


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