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We covered three (of five) primary plant KINGDOMS: protista, fungi, and plantae. "Kingdom" means that they all evolved from a common ancestor.
The PROTISTA kingdom consists of algaes and diatoms. These seem to be primordial sea-based tiny creatures. Diatoms are so tiny that we can barely see them, like krill. Diatomacious earth is one kind of diatom. When diatoms die, they leave behind their hard little shells. I wonder if the crust that slowly develops on top of the desert Earth in Joshua Tree National Park (CA) if composed of deceased diatoms. We focused on algaes, which include seaweeds. The pH of the blood that runs through our bodies mirrors the ocean's pH; our blood is very closely related to seawater! Is this why eating seaweed helps to build healthy blood? Seaweeds make up half of lichens (which are symbiotic relationships between algae and fungi). They are thin enough to take in and put nutrients back out into the water. Algaes (and seaweeds too) don't make seeds. They can both sexually and nonsexually reproduce.
The FUNGI kingdom includes mushrooms, yeasts, molds, mildews, and rusts. Mushrooms are the obvious fruiting bodies of fungi. Mycellium is the fungi itself, often threadlike. If you pick a mushroom, you can see the white threads of connection running beneath the Earth- this is mycellium. I like to think of it as a huge net right beneath the soil, binding all the Earth together, recycling dead matter into fresh energy right beneath our feet. (But what about concrete jungles?) Fungi reproduce with spores. In class, we ended up talking a lot about reproduction because this is how life continues: we grow, we procreate, we die. And if we don't procreate, then there is no continuation of life. (I am speaking from the perspective of mushrooms, but also human beings.) Fungi are all heterotrophs (live off of photosynthetic organisms), instead of autotrophs (who photosynthesize and produce their own food from sunlight, CO2, and water.)
The PLANTAE kingdom takes us to our next section...
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The PLANTAE kingdom includes bryophyta, pteridophyta, and spermatophyta. (These are great names to name your children!)
The BRYOPHYTA plants are nonvascular spore-producing plants that include mosses, liverworts, and hornworts. These are the oldest plants in the world, from dinosaur days! Mosses have rhizoids, instead of roots; they anchor loosely to the soil. Mosses take in water directly from the atmosphere, like a sponge. They are autotrophs that photosynthesize their nutrients. The difference between spores and seeds: seeds are baby plants, containing all the genetic information needed to create a whole new plant. Spores only contain half the gametes (specialized reproductive cells) to create a new plant. Thus, spores need to meet another spore of the opposing sex to reproduce. Mosses need rain or wetness to reproduce. When the rain droplets (or wind, or whatever instigates the movement) hit the moss arms (I am unsure of the technical term of the non-leafy moss arms), the male spores go flying from one moss arm off to meet a female spore on another moss arm. If the male spore lands below the female spore, then it will use a process called chemotaxi (amazing) to travel up the moss arm to meet the female spore. The male spores can only chemotaxi in water, that's why you will find more mosses in wet environments, such as in Taiwan (gorgeous). When the male spores chemotaxi up the moss arm, it propels itself with a little tail, much like a male sperm cell, or tadpole. Except that it has two tails! Another amazing quality of mosses is that they can dessicate (dry up) and live! They need water to reproduce, but can dry up for a long period of time, and then come back to life (I will try this one day).
The PTERIDOPHYTA ("pterido" means "winged" and "phyta" means "plants") plants are spore-producing and vascular plants that include ferns, club mosses, and horsetails. These plants came after the Bryophyta plants, with real roots that pull nutrients from the soil, allowing them to grow taller and closer to the sun. These plants dominated during dinosaur days. When they died, they turned into coal and other natural resources that we are still utilizing today. Vascular plants have vascular bundles that carry water and nutrients throughout the plant. They are like the circulatory system of the plant. Two groups of cells form the vascular system of plants: the xylum and phloem. Xylum carries water and dissolved nutrients from the roots and soil up to the topmost extremities of the plants, while phloem carries the products of photosynthesis (usually sugar) down through the plant. Xylum draws nutrients up, phloem carries nutrients down. In a tree, the xylum becomes the hardened heartwood in the center of the tree trunk. The phloem becomes the bark. Over time, the hardened rings of xylum and phloem (the vascular bundles) become the tree's age rings: you can watch the aging process of the tree by looking at the patterning of its vascular bundles in a cross section of the tree trunk. The vascular bundles are the most chemically rich part of the tree, most often used for medicine (such as slippery elm bark, cherry bark, willow bark, etc.) These plants defend themselves by being silicacious (rough bodied). They don't contain much medicinal value. Ferns reproduce by spores. When the fern fpores fall to the ground, they turn into a prothallus (sometimes called just a "thallus.") The prothallus is a sporophyte (where sex cells are made) that contains both the male sex cell (antheridia) and female sex cell (archegonium). Once the prothallus falls on the ground, the antheridia (male) swims over to fertilize the archegonium (female). Then, the prothallus grows small roots and starts becoming the new fern (gametophyte).
SPERMATOPHYTA ("sperm" means "seed") are vascular seed-producing plants that are most of the plants that we know today. Next section!
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SPERMATOPHYTA plants are either angiospermae or gymnospermae.
ANGIOSPERMAE ("angio" means "vessel," and "sperm" means "seed") are flowering plants that have seeds with ovaries. These comprise 90% of the roughly 250,000 species of plants on our planet. Angiospermae are either MONOCOTYLEDONS (when seeds open, one leaf emerges) or DICOTYLEDONS (when seeds open, two leaves emerge). (A "cotyledon" is the leaf that emerges from the seed.) Most plants are dicots, with 4-5 flowering parts, vascular bundles on the outside (well organized), and leaves with reticulate veins (think of your usual leaf). Monocots have 3 flowering parts, and less changeable. They have leaves with parallel veins and randomized vascular bundles (with no growth rings). These plants fall down easier, as they don't make heartwood. 90% of woody plants are dicots.
GYMNOSPERMAE ("gymno" means "naked," and "sperm" means "seed") are wind-pollinated plants that include conifers, ephedra, and gingko. They have unisexual flowers (staminate/male-only or pistillate/female-only). These plants developed before insects came along to help pollinate flowers. Thus, they are wind pollinated. The ovule (female part) is not in an ovary; their ovules are exposed to the wind (like a pine cone). The wind will blow the pollen (male parts) around to meet and fertilie the ovules (female parts). These plants are either monoecious or dioecious. Monoecious plants have both male and female flowers on the same plant, such as corn and conifers. Dioecious plants have male plants and female plants, such as ephedra, gingko, and marijuana.
Let me know if you have any questions about any of this phylogeny information! I am very new to phylogeny, and find it fascinating. Every person has a unique history (herstory) and story, and plants do as well! In class, I feel like it's story-time: I settle back into our comfy chairs and blankets as it's raining outside, sip steaming herbal tea, and listen to 7song tell dramatic true stories about plants and how they procreate and how our world and our medicine came to be. Love it.
(photo of yucca from Taiwan)
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Jiling . 林基玲
Jiling . 林基玲
. wild . creative . spirit
626.344.9140 / skype: Lin.JiLing
