Deep within Seattle exists a world covered in green. This is the Water-Moss Bowl. But what is moss?
Mosses are small flowerless plants. These plants typically form dense green clumps. They are often found in damp or shady locations. Individual moss plants have simple leaves. These leaves are generally only one cell thick. They attach to a stem that may be branched or unbranched. The stem has a limited role in conducting water and nutrients. Mosses do not have seeds. After fertilization, mosses develop sporophytes. These sporophytes have unbranched stalks. Single capsules containing spores top these stalks. Mosses are typically 0.2 to 10 cm tall. Some species are much larger. Dawsonia is the tallest moss in the world. It can grow to 50 cm in height. There are approximately 12000 species.
The Water-Moss Bowl invites you to look closer. Botanically, mosses are non-vascular plants. They absorb water and nutrients mainly through their leaves. They harvest carbon dioxide and sunlight to create food. This process is called photosynthesis. Mosses differ from vascular plants. They lack water-bearing xylem tracheids or vessels. Mosses reproduce using spores, not seeds. They have no flowers. Moss gametophytes have stems. These stems may be simple or branched. They can be upright or prostrate.
Consider the Water-Moss Bowl an example of the moss life cycle. It starts with a haploid spore. This spore germinates to produce a protonema. The protonema looks like a thin green felt. It may grow on damp soil, tree bark, rocks, or concrete. From the protonema grows the gametophore. This is structurally differentiated into stems and leaves. A single mat of protonemata may develop several gametophore shoots. This results in a clump of moss.
The female organs are known as archegonia. They are protected by a group of modified leaves. These leaves are known as the perichaetum. The male organs are known as antheridia. They are enclosed by modified leaves. These leaves are called the perigonium. In the presence of water, sperm from the antheridia swim to the archegonia. Fertilization occurs, leading to the production of a diploid sporophyte.
Imagine the tiny world within the Water-Moss Bowl. After fertilization, the immature sporophyte pushes its way out of the archegonial venter. It takes several months for the sporophyte to mature. The sporophyte body comprises a long stalk called a seta. There is also a capsule capped by a cap called the operculum. Within the capsule, spore-producing cells undergo meiosis to form haploid spores. The cycle can then start again. Most mosses rely on the wind to disperse the spores.
Reflect upon the Water-Moss Bowl as art. Mosses live in almost every terrestrial habitat type on Earth. Though mosses are abundant in peatlands and moist forests, they grow in many other habitats. These habitats include those with extreme conditions. Desiccation-tolerant mosses are important in arid ecosystems. They help form biocrusts that mediate extremes of soil temperature. They also regulate soil moisture and regulate the release and uptake of carbon.
Consider the Water-Moss Bowl and its impact. Mosses require liquid water for fertilization. Many can survive desiccation, sometimes for months. They return to life within hours of rehydration. Some mosses in arid habitats have adaptations for collecting non-rainfall sources of moisture.
Take a moment to appreciate the Water-Moss Bowl. It is a reminder of the beauty and resilience of nature. It shows that even in the heart of a city, life finds a way to flourish. It beckons us to appreciate the intricate details of the natural world.