Botany Blog Plants of the Northeastern U.S.

January 17, 2010

Passiflora x belotii

Filed under: Plant-Insect Interactions — admin @ 02:31

Passiflora x belotii is the name given to the hybrid of P. alata and P. caerulea. It is a sterile hybrid that will not produce fruit but is a prolific bloomer when given plenty of light. The flower shown here was taken from one of my plants that was erroneously labeled P. incarnata at the nursery where I bought it.

Passiflora x belotii

There are over 450 recognized species in the genus Passiflora (Vanderplank 1996). Most are vines, but a small number can grow as trees (e.g. P. lindeniana). Most people recognize passionflowers as having purple and white flowers, but there are species that produce white, pink, yellow, red and even orange flowers. The flowers of the hybrid shown here are very fragrant with a scent similar to that of the fruit of P. edulis. The foliage of passionflowers is toxic primarily due to the presence of cyanogenic glycosides. When a leaf is chewed by an insect, these glycosides interact with ezymes in the leaf (much like when a glow stick is “broken” allowing the chemical components to mix) and release hydrogen cyanide as a by-product. A group of tropical and subtropical butterflies (subfamily Heliconiinae) have co-evolved with plants in the genus Passiflora and have developed the ability to somehow metabolize these compounds and use them as a defense against predators (Engler et al. 2000).  One of the better known species is the red postman butterfly, Heliconius erato, which is often displayed in butterfly houses at botanical gardens and nature centers.

Heliconius erato

This image was taken at Hershey Gardens in their butterfly house. It is worth noting that the garden does not breed or raise their butterflies; they purchase pupae from places in the tropics that rear caterpillars, some of which are sold while others are released back into the wild to aid conservation efforts in areas where suitable habitat is diminishing.

Engler, H.S., Spencer, K.C. and Gilbert, L.E. 2000. Insect metabolism: Preventing cyanide release from leaves. Nature, 406, 144-145.

Vanderplank, J. 1996. Passion Flowers, 2nd ed. The MIT Press. Cambridge, MA.

January 1, 2010

Water Net (Hydrodictyon reticulatum)

Filed under: Algae — admin @ 16:00

It would seem that the subject of my posts keep getting smaller and smaller. These images are of a common green algae (phylum Chlorophyta) commonly known as Water Net. It gets its name from the pentagonal or hexagonal branching pattern of the filaments making up the body (thallus) of the algae. These specimens came in on a sample of Chara, another green algae that is considered to be the closest living relative to plants. I took a sample of the Chara out the other day to photograph and left the sample in a dish of water under some lights. After about a week these little green ‘bubbles’ started appearing and have continued to get progressively larger.

Hydrodictyon reticulatum

I was really curious what this stuff was but couldn’t really find anything that fit the description. I was already aware that water net was growing in the tank where I am keeping the Chara, but the filaments on these were not visible to the naked eye. It wasn’t until I got out a hand lens that they became apparent.


Apparently they can form these somewhat spherical colonies that just keep expanding as the thallus divides. I got one good closeup showing how each filament is connected to two other filaments, which creates the unique branching pattern and allows the colony to take on a 3-dimensional form.


Algae in the genus Hydrodictyon are isogamous (gametes all alike) and the cells are coenocytic (multinucleate). Dictyo is Greek for net-like, so the genus means the same as the common name.

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