Thursday, August 27, 2015

A Friendly Approach to Grasses, Part 2

In the onrushing course of evolution, as flowering plants gained a majority presence on land, the grassy clan adapted to nearly every niche. With their growth point located near or below ground level - rather than at the stem tip - they could more successfully recover from grazing, trampling, fire, drought, and climate severities.

Three grassy plant families now present at Halibut Point are closely enough related to be grouped together as Graminoids: the true grasses Poaceae, the sedges Cyperaceae, and the rushes Juncaceae.
If the plant before you has long narrow leaves with parallel veins, very likely it's a Graminoid. If its stems are circular and hollow with nodes swollen where leaves join the stems, think true grass-Poaceae. If the stems are edgy and probably triangular in cross section, think sedge-Cyperaceae. If the stems are circular, solid, often wiry-looking, with leaves that usually sheath the stems, think rush-Juncaceae.

Calmagrostis canadensis, Canada blue joint
Across the moister areas of the Halibut Point heath at this moment a tall grass Canada blue joint is blooming with a cereal-looking inflorescence.

Calmagrostis canadensis closeup
It shows the kinds of features that have made grasses an inseparable part of human civilization, the backbone of agriculture and livestock pasturage. Wheat, corn, rice, all the cereal grains have their origins as grasses. The Poaceae sugar cane and bamboo also make extensive contributions to mankind's economic life.
Danthonia spicata, Poverty grass
Many grasses adapt to dry conditions by approaching dormancy in hot weather, even to the extent of shedding their leaves once the flower stalk is launched. A considerable portion of a grass plant's succulence is stored protectively within the root system. People commonly prod their lawns into mid-summer growth only by watering them regularly through the heat.

Setaria faberi, Chinese foxtail

Setaria viridis,  Green foxtail
There are upwards of thirty species of grasses to be found at Halibut Point. Getting oriented to the distinctions can be daunting. A friendly guide opens doors.

Chris Leahy reverses his binoculars for a close look.
When we took a tour together, ornithologist-field botanist Chris Leahy demonstrated a resourceful way to magnify the details of a grass flower.

Chris reads the flora along with other landscape features as one picture. Scanning the plants at eye level he predicts terrain, soil qualities and moisture. Looking down at ground characteristics he predicts specific plants. Along with knowing 'jizz' - the general visual impression of various plants - as well as the cycle of their seasonal development, and pertinent historical factors, he is well prepared to name the Graminoids we encounter without using identification keys. He narrates an ecological story.
Schizachyrium scoparium, Little bluestem
Little bluestem is one of the native grasses that Chris champions as a crucial constituent of the 'leaner' habitats on Halibut Point. It tolerates hot, dry soils with little fertility. It is the exclusive host (that is, food) for the caterpillar stage of some species of butterflies.

A wet area with a localized ecosystem
Quarrying operations left scattered pits that have naturalized into damp fens where we find Canada rush (Juncus canadensis) Toad rush (Juncus bufonius), Three-square sedge (Scirpus americana), and Wool sedge (Scirpus cyperinus).

Juncus tenuis, Path rush
Path rush seeds developing
Juncus tenuis seems exceptional among local Juncaceae in its ability to adjust to both damp and dry areas. Tough and wiry it tolerates foot traffic and contributes to the groundcover in compacted walkways throughout Halibut Point, earning the name 'path rush.'
Juncus effusus,  Soft rush
The more statuesque Juncus effusus is a fiber of choice source for weaving baskets and mats, resulting in the common name 'soft rush.'

Soft rush seeds developing
Circular stems, miniature lily-like flowers, and nutty-looking seeds give rush plants a characteristic look.
Carex crinita, Fringed sedge
Cyperaceae family members like this Fringed sedge tend to have clumps of flat-leaved arching foliage with 'edgy' flower stems that are triangular in cross-section.

Cyperus pseudovegetus, Marsh flatsedge
Most of the Cyperaceae grow in wet areas where their architectural forms stand pleasingly above the water surface.
Scirpus microcarpus, Barber-pole bulrush
One of the more ornate Cyperaceae, Barber-pole bulrush, distinguishes itself with a colorful stem pattern.
Barber-pole bulrush in a water-retentive pocket
It has established itself in a particularly fortunate location for Halibut Point State Park visitors.

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