Wednesday, August 20, 2008

Saxifraga oregana

Another member of the Saxifragaceae family is pictured to the left: Saxifraga oregana (Oregon saxifrage). This beauty was photographed near the upper Deschutes river. A detail of the inflorescence is pictured below. This species occurs in bogs, wet meadows or streambanks. This individual occurred alongside Fritillaria lanceolata (chocolate lily) and Trillium chloropetalum (sessile trillium), two members of the Liliaceae family.Leaves of this species are quite large for the family, generally greater than 5 cm in length with the characteristic wavy margins. ("sinuate or remotely denticulate" in Hitchcock). Sinuate = with a strongly wavy margin. Denticulate = dentate with very small teeth. Dentate = toothed along the margin, the teeth directed outward rather than forward.


Sunday, August 10, 2008

Lycopodium clavatum

Lycopodium clavatum (running clubmoss) - Lycopodiaceae. An example of a seedless vascular plant - so reproduces by spore similar to liverworts but also has true conductive tissues, xylem and phloem. Unlike the liverworts, club mosses are homosporous (have only one kind of spore) and spores give rise to bisexual gametophytes.
The above ground portion pictured rather blurrily above is the rhizome. The gametophytes of some club mosses, including this species, grow below ground, are non-photosynthetic and maintain a mycorrhizal relationship with fungi. Strobili are borne on aerial stems attached to the rhizomes (pictured at left). Strobilus (pl. strobili) = a cone-like cluster of sporophylls on an axis. Sporangium borne on the strobili release spores that develop into the gametophyte which bear both archegonia and antheridia. During fertilization, biflagellated sperm produced by the antheridium swim to the egg produced by the archegonium (the presence of water is required). The newly produced sporophyte may remain attached to the gametophyte for a long time but eventually detaches to become a separate individual. (Plant Biology - Raven, Evert, Eichhorn)

Monday, August 4, 2008

Liverworts


Marchantia polymorpha (lung liverwort) - Marchantiaceae: a thalose liverwort/hepatic, pictured above surrounded by moss. Liverworts do not possess stomata and are non-vascular (except for water-conducting strands in the gametophytes of a few genera which I feel like I observed when pulling the archegoniophore apart from the gametophyte of this species) and reproduce by spore. Liverworts are a member of the Marchantiophyta division, part of the Bryophytes.

Because liverworts are non-vascular they do not possess real roots but rather rhizoids. Rhizoid = a root-like structure lacking conductive tissue (xylem and phloem). The archegonia are pictured above, these are the female reproductive structures - motile sperm from the male gametophyte (antheridiophore) are splash-dispersed to the female. Fertilization occurs leading to a zygote > an embryo > a young sporophyte. Spores are eventually released from the mature sporophyte and would be located on the underside of the archegoniophore as pictured below (mature sporophytes aren't visible and probably already dispersed).
Marchantia also conducts asexual reproduction through gemma cups on the leaves - a gemma cup is visible in the first photograph on the lower-most leaf pictured. Gemmae are splash-dispersed from the gemma cup onto soil and clones result. Gemma (pl. gemmae) = a bud or bud-like structure, or cluster of cells which separate from the parent plant and propagate offspring plants.

Sunday, August 3, 2008

Monotropa hypopithys (pinesap)

Monotropa hypopithys (pinesap) of the Monotropaceae family. This individual was actually photographed in Newberry Nat'l Volcanic Monument just south of Bend, OR. The range of the species extends from BC to California all across the US. This plant is an example of a myco-heterotroph. Myco-heterotrophs lack chlorophyll and the ability to photosynthesize and rather, the plant derives carbohydrates through a parasitic relationship with certain kinds of fungi. The connection between the two occurs through the roots of the plant and the mycelium of the fungus. The WTU herbarium has "placentation axile rather than parietal" listed as a distinguishing characterisitic. Parietal placentation = ovules attached to the walls of the ovary. Axile placentation = ovules attached to the central axis of an ovary with two or more locules. Locules = the chamber or cavity ("cell") of an organ, as in the cell of an ovary containing the seed.