Podostemum ceratophyllum

Podostemum locality on the Mount Hope River in Mansfield, Ct.

Podostemum ceratophyllum, or Hornleaf Riverweed, is the only really good example in Connecticut of a flowering plant that is a rheophyte. Rheophytes are aquatic plants that exclusively live attached to rocks in rapids or waterfalls, in clean, violently fast-moving water. This almost absurdly specialized ecological niche is occupied by species in various unrelated plant families, included a couple of tropical species of Utricularia, the carnivorous bladderworts, but the most diverse family that is exclusively rheophytic is the Podostemaceae.

Podostemum ceratophyllum in the Mount Hope River.

 

 

The Podostemaceae are peculiar things, with a morphology that is difficult to interpret, involving a certain degree of ambiguity between the three classical types of plant organ: roots, stems and leaves. A green, photosynthetic, creeping holdfast-type organ grips the rocks on which the plants grow, and in Podostemum and most other genera this is root tissue (some of the research establishing the homology of Podostemum holdfasts was conducted by UConn's own Tom Philbrick). The roots give rise internally to root born shoots, which bear what are probably leaves (but may be in some cases leaf-like stems) as well as the flowers. The structural oddity of riverweeds, presumably resulting from adaptations to their extreme environment, has also historically made the relationships of the family difficult to determine. Modern molecular evolutionary work seems to have finally placed the Podostemaceae firmly within the order Malpighiales, closely related to the Hypericaceae (Saint John's Wort family).

Podostemum ceratophyllum fruits.

The riverweeds flower and fruit during periods of low water, when the plants are exposed to air. In New England, flowering season is late summer, when there is often something of a drought and the rivers are at their lowest ebb. The flowers are small and non-showy, and probably self-pollinated or wind-pollinated. The fruits are little dry capsules that look quite a bit like moss sporangia (spore capsules). The seeds are sticky when wet, and able to glue themselves to rocks so that they stay in place when their habitat is flooded again.  

Podostemum ceratophyllum only grows in certain special sites, not only needing rock submerged in clean, cool, well-aerated, swiftly flowing water, but also being restricted to exposed, sunny stretches of river. It is apparently a species in decline as a result of development and agricultural runoff, vulnerable especially to sediment and nutrient pollution in its water. One of the  local riverweed sites on the Natchaug River in Chaplin is still extant, but the plants don't seem to be as abundant or healthy as they were 30 years ago, when I was first shown the spot. 

Podostemum locality on the Natchaug River, Chaplin, Ct.

Various people have attempted to cultivate Podostemum and other riverweeds, as far as I know without any long term success. Plants on cobbles moved to aquariums with vigorous aeration and water circulation will languish for a few weeks, then decline and disappear. Seeds have been germinated in artificial conditions, but the seedlings don't seem to persist. It should be possible to grow Podostemum from seed to seed indoors, but it would perhaps require more attention to light, water movement, temperature and water chemistry than anyone has been willing to lavish on a river weed up to this point. 

 

 

Carnivorous Plant Show

Nepenthes edwardsiana at the New England Carnivorous Plant Society Show.

The New England Carnivorous Plant Society held its annual show this past weekend, and as usual the membership displayed and sold a fantastic array of plants. Attendance was excellent, as well, with something around 1500 visitors on Saturday alone. The show took place at Tower Hill Botanical Garden in Massachusetts, Worcester County Horticultural Society's immaculately maintained complex in the Worcester suburbs. In earlier phases of the NECPS's existence, the show was held at Roger Williams Park in Providence (and one time at the University of Rhode Island), but the event has become a popular autumn tradition at Tower Hill over the past couple of years.

Visitors to the carnivorous plant show, Saturday Morning.

The American Pitcher Plant (Sarracenia) table was packed solid with plants.

Emmi K's comprehensive collection of the bladderworts (Utricularia) of New England. Emmi and some friends travel around to swamps and bogs in the summer, collecting bladderwort specimens, then use the plants to create an educational display.

A big pot of a giant Venus' Flytrap cultivar, Dionaea muscipula 'B52'. The name B52 apparently derives from a label code in Henning Von Schmeling's flytrap breeding program, and has nothing to do with the bomber (or the band).

The very rare and almost shrub-like South American pitcher plant Heliamphora tatei.

Another "Sun Pitcher" species that is almost never seen in cultivation, Heliamphora sarracenioides.

An art installation made of woven saplings on the Tower Hill grounds: "Wild Rumpus" by Patrick Dougherty.

Carnivorous Plant Meeting at UConn

Carnivorous plant collection at the UConn Ecology and Evolutionary Biology Teaching and Research Greenhouses.

The New England Carnivorous Plant Society held their May 14 meeting at the University of Connecticut. Activities included a tour of the botanical teaching collections, which include a good selection of carnivores. After the business portion of the meeting was concluded, some of us headed to the Dunhamtown Forest preserve, less than a mile from the center of campus, to look for some of the local carnivorous plants and other spring wildflowers. 

Dunham Pond, Storrs, Ct.

We hiked on the trails to the bank of Dunham Pond. The pond is a natural body of water, and is probably a kettle pond dating back to the last ice age, formed as a depression left behind by the melting of a large residual mass of ice left behind by the glaciers. Dunham pond hosts several species of aquatic Utricularia (bladderworts), but it was too early to see any sign of these. Purple Pitcher Plants (Sarracenia purpurea) also grow in the preserve, but in a very difficult to access swampy thicket, so we didn't get chance to visit them this time. There is an old herbarium record of Sarracenia flava, one of the large, upright southern pitcher plants, naturalized at Dunham Pond. These must have been planted out by a local botanist, and there is no sign of them surviving today.

Arisaema triphyllum, Jack-in-the-Pulpit, in the Dunhamtown Forest.

Various spring wildflowers were in bloom along the trails, such as Canada Mayflower, Wood Anemone, and Jack-in-the-Pulpit, one of our local aroids. People often misidentify the inflorescences of Jack-in-the-Pulpit for pitcher plants, but no one from the NECPS was going to make a rookie mistake like that.

Drosera rotundifolia, the Round-leaf Sundew.

In the end, the only carnivore we saw at Dunham Pond was Drosera rotundifolia. This is the only sundew (of two potential local species) that occurs at the site. The plants were fairly abundant on Sphagnum moss tussocks, and sometimes growing directly in rotting wood on waterlogged fallen tree trunks.

Sarracenia purpurea in Willington, Ct.

A few of us took a break after the walk at the UConn Dairy Bar, and decided to head to another nearby bog, in Willington, Connecticut, to see Purple Pitcher Plants. The bog, a classic site for UConn biology field trips, is a floating Sphagnum mat with one of the most vigorous populations of S. purpurea that I know of, and also plenty of Round-leaf Sundews. It was a little early for the pitcher plants, which were just starting to produce flower buds and only had overwintered pitchers from last season. 

Rhododendron canadense, Rhodora, in early May, Willington, Ct.

Rhodora, a Rhododendron of bogs and swamps in the Northeast was in full bloom. This low shrub was growing in a couple of scattered spots on the Sphagnum mat, among the pitcher plants and a much more abundant ericaceous shrub, Chamaedaphne (Leatherleaf).

Autumn Miscellany

Darlingtonia californica at the NECPS Show.

Earlier this month, the New England Carnivorous Plant Society held its annual show. As usual there were plenty of superbly cultivated plants on display (and plenty more for sale), and some well known people from the carnivorous plant community in attendance. This Darlingtonia was one of the more impressive horticultural feats; I don't think I've ever seen one so large cultivated in the East. I've never been able to keep them alive for more than a year or two, myself; they definitely tend to decline in our warm, humid summers.

The venue was a new one for the NECPS: Tower Hill Botanical Garden, near Worcester, Massachusetts. Tower Hill is a beautiful location and the public turnout was quite high, with about 2200 paid guests for the weekend. The only minor issue was that space was pretty tight, with the show and most of the vendors packed into one conference room, because of some scheduling conflicts.

Part of the bladderworts of New England display.

Several of the NECPS regulars collaborated to collect fresh specimens of almost all of the dozen or so bladderwort (Utricularia) species that are native to New England. They put on a great educational display and managed to turn up some plants that are found at a limited number of sites, like U. inflata, which supports its flowers above the surface of ponds on spongy, star-shaped floats.

The bees had a good summer and a decidedly better than average fall, which was nice after a cold start to 2015 with more winter colony losses than I'd like to see. It's been on the dry side in Connecticut, but the bees have apparently been finding plenty of flowers. Most colonies have packed away enough autumn honey to get themselves through the winter without any supplemental sugar feeding, which was unexpected. Looks like I'll be holding on to the stack of warehouse club 25 pound sugar bags in the basement until next spring, at least.

I tried to photograph the supermoon lunar eclipse last Sunday, and took a few shots that turned out OK. I don't think my camera was up to the task of capturing the earth's shadow starting to cross the face of the moon. Photos of the total eclipse worked better, without the overwhelming contrast of shadowed and sunlit portions of the moon messing up the exposure.

2015 turned out to be a "mast year" for apples (and oaks, too), with all of the feral or unmanaged trees around town producing crops of fruit that are so heavy that I've seen a number of snapped branches. Mast years occur irregularly; maybe about every third autumn will have this kind of super abundance of apples. The fruits are remarkably free of worms and disease, which is what you would expect based on one idea about the adaptive significance of masting: when all the trees in an area are synchronized in a mass fruiting event, pests can't reproduce quickly enough to take advantage, and then starve during subsequent non-mast years when very few fruits are produced. There is probably a contribution from the vagaries of weather to the masting phenomenon. Pollination limitation might also be involved in synchronizing masting, with any trees that flower heavily in a non-mast year experiencing poor pollination and low fruit set due to a lack of mates, and presumably maintaining reserves that would have otherwise gone into fruit to flower strongly again the next spring.

Aponogeton madagascariensis Seeds

Looking down into a large aquatic tank with a pot of Aponogeton madagascariensis.

 Aponogeton madagascariensis, the Madagascar Lace Plant, is a submerged aquatic with naturally occurring holes in its leaf blades. The leaves are like window screen, with a network of veins and photosynthetic tissue, but with gaps in the leaf between the veins. Aquatic plants have more difficulty than terrestrial plants obtaining carbon dioxide, because gas diffusion is much slower in water than in air; the lacy leaves of A. madagascariensis probably are an adaptation to create more surface area for gas exchange.

Aponogeton madagascariensis inflorescence, late summer.

As is the case with many aquatic plants, A. madagacariensis sends its flowers above water for pollination. The flowers seem to be able to self-pollinate and if conditions are right give rise to clusters of small, green, horn-shaped fruits a few weeks later.

Aponogeton madagascariensis fruiting shoot shedding floating seeds.

When ripe, the fruits split open and release seeds. The seeds are a milky violet color and have a water-repelling waxy surface, enabling them to float and disperse away from their parent plant. After floating for a day or two, the seed coat becomes clear and water-logged, and splits open to release the green embryo inside, which sinks to the bottom. I've been gathering the seeds and putting them in submerged pots of sand and soil, and hope to get some germination and Lace Plant seedlings soon.