Volume VII: Nature — Chapter 9: The Plant Kingdom (Deepening)
"The root does not argue with the soil. The leaf does not argue with the light. A plant is patience made visible. It stands still — and outruns everyone." — From the "Book of Roots," a sacred Xha'Ruun text, the Era of Unity
Related sections: → see [Volume I, Ch.17, "The Flora of Théxar"], → see [Volume I, Ch.11, "Ecology"], → see [Volume I, Ch.21, "Ecosystems"], → see [Volume VII, Ch.03, "Marine Ecosystems"], → see [Volume VII, Ch.10, "Symbiosis and Coevolution"], → see [Volume VII, Ch.13, "Biosphere Interactions"], → see [Volume IX, Ch.03, "The Natural Lexicon"] Length: 15 pages
Introduction
The survey chapter of Volume I established the fundamental parameters of the flora of Théxar: chromophyll with an absorption peak at 570 nm, ~380,000 described species, dominance of the division Chromophyta (→ see [Volume I, Ch.17, "The Flora of Théxar"]). This chapter deepens that description: it examines the anatomy and physiology of the planet's plants, unique life strategies, sixfold growth cycles, and specialized photosynthetic adaptations.
Three circumstances make the flora of Théxar fundamentally different from a terrestrial-type flora. The first is chromophyll photosynthesis under the orange spectrum of the star Khar'Vex, which set the characteristic "living silver" color of the vegetation. The second is silicon biomineralization, pervading the whole flora: from the cell walls of mosses to the bark of centennial trees. The third is sixfold periodicity: most plants of Théxar pass through six phases of vegetation per year and add six annual rings, inheriting the senarity of the biosphere (→ see [Volume I, Ch.20, "The Origin of Life"]).
9.1 The Photosynthetic Apparatus
9.1.1 The Antenna Complex
The pigment system of the plants of Théxar is built around chromophyll, but is not limited to it. The photosynthetic efficiency of 4.2% is achieved by the work of a coordinated antenna complex of five pigments (→ see [Volume I, Ch.17, "The Flora of Théxar"]).
| Pigment | Color | Absorption peak | Localization in the leaf | Role |
|---|---|---|---|---|
| Chromophyll a | Copper-red | 570 nm | Reaction center | Primary, photosystem I |
| Chromophyll b | Golden | 540 nm | Light-harvesting complexes | Auxiliary, photosystem II |
| Theta-carotene | Orange | 480 nm | Periphery | Photoprotection |
| Ther xanthophyll | Yellow | 450 nm | Inner antenna | Heat dissipation, Ther cycle |
| Seriflavin | Purple | 620 nm | Lower side of the leaf | Capture of reflected light |
9.1.2 The Double-Sided Leaf
The typical Chromophyta leaf has an asymmetric pigment structure: the upper side is saturated with chromophyll a/b (works on the direct light of Khar'Vex), the lower with seriflavin, a purple pigment that captures light reflected from the soil and neighboring leaves. In the understory of the jungles up to 23% of a leaf's photosynthesis is provided by upward light that has passed through the canopy and been scattered in the lower tiers.
9.1.3 The Ther Cycle
The heat-resistant variant of the xanthophyll cycle — the Ther cycle — protects the reaction centers from overheating at peak illumination. With an excess of energy, Ther xanthophyll reversibly converts into theroflavin, which dissipates 78% of the excess energy as heat in 2–4 minutes. Thanks to this cycle, the plants of Théxar endure brief illuminances up to 1,100 W/m² without damage — even though photosynthesis saturates already at 420 W/m².
9.2 The Vascular System and Silicon
9.2.1 Silicon Reinforcement
The uniqueness of the flora of Théxar is the ubiquitous deposition of amorphous silica (SiO₂) in the cell walls of the conducting elements.
| Division | SiO₂ content in dry mass | Tissue hardness (Mohs) | Water transport |
|---|---|---|---|
| Chromophyta | 2–9% | 2.5–4.0 | Vessels + tracheids |
| Silophyta | 8–35% | 3.5–5.5 | Tracheids only |
| Thexophyta (epiphytes) | 3–7% | 2.0–3.0 | Moisture capture by bark |
| Thalophyta (algae) | 4–18% | — | Osmotic |
| Bryoforma | 5–22% | — | Capillary |
Silicon performs four functions: structural (rigidity), protective (against herbivores), radiative (UV shielding), and hydraulic (reduction of cavitation in vessels under water stress). The silicon ring around the vascular bundles prevents the collapse of a vessel at negative water pressure — an adaptation that allowed Chromophyta to reach heights of 100+ sha.
9.2.2 Concentrating Metabolism
More than 60% of the vascular plant species of Théxar use concentrating metabolism: CO₂ is actively pumped into the bundle-sheath cells, where chromophyll works at a substrate concentration 6–8 times higher than atmospheric.
| Parameter | C₃-like | Concentrating |
|---|---|---|
| Share of species | ~40% | ~60% |
| Photorespiration (losses) | 22–30% | 8–12% |
| Transpiration (rel.) | 100 | 75 |
| Photosynthetic efficiency | 3.0–3.6% | 4.2–4.9% |
| Ecological optimum | Humid forests, coasts | Dry savannas, steppes, highlands |
9.3 Systematics: A Deeper Survey
The taxonomy of the flora of Théxar is fixed in Volume I; here refined data and evolutionary relationships are given.
| Division | Described species | Estimated total | Root clade | Key feature |
|---|---|---|---|---|
| Chromophyta | 120,000 | ~155,000 | ~620 million cycles | Chromophyll a/b, vessels with silicon |
| Silophyta | 45,000 | ~60,000 | ~380 million cycles | Silicon skeleton, tracheids |
| Thexophyta | 38,000 | ~52,000 | ~340 million cycles | Epiphytism, H₂S filtration |
| Thalophyta | 32,000 | ~46,000 | ~1,050 million cycles | Thal phycobilin, gametes |
| Bryoforma | 28,000 | ~41,000 | ~900 million cycles | Parenchymatous, without vessels |
| Others (incert.) | 117,000 | ~166,000 | — | — |
| Total | 380,000 | ~520,000 | — | — |
9.3.1 Chromophyta — Red-Leaved
The dominant group of the terrestrial flora, 6 subclasses:
| Subclass | Species | Form | Example | Range |
|---|---|---|---|---|
| Tor-Chroma (giants) | 8,400 | Trees 40–104 sha | Tor-Khar | Jungles |
| Ven-Chroma (forest) | 31,000 | Trees and shrubs 4–67 sha | Ven-Shar | Temperate forests |
| Khar-Chroma (grasses) | 26,500 | Herbs 0.2–3.7 sha | Khar-Grain | Savannas, steppes |
| Thal-Chroma (coastal) | 19,200 | Mangroves, hygrophytes | Mangro-Ven | Coasts |
| Mor-Chroma (lianas) | 12,400 | Lianas 10–61 sha | Rhu-Koss | Jungles, forests |
| Nur-Chroma (ephemerals) | 22,500 | Annuals | Ash-Grass | Deserts, steppes |
9.3.2 Silophyta — Silicon Plants
A division endemic to the dry zones of Théxar, with no direct terrestrial analogues. Silicon in their walls is not auxiliary but the primary construction material.
PROFILE: Silophyta
Parameter Value SiO₂ content 8–35% of dry mass Forms Shrubs, succulents, grasses, cacti Maximum height 4.9 sha (silicon "trees" of the Raal plateau) Range Shan Desert, highlands of Rhuval, dry zones of Vexar Water regime CAM-like (nocturnal stomata) Reproduction Seeds with a silicon coat; vegetative
The silicon "trees" of the Raal plateau (genus Sha-Tor) are a unique case: perennial silophytes up to 4.9 sha tall with true growth rings. Their age reaches 2,800 cycles — the record of plant longevity on Théxar.
9.4 Life Strategies
9.4.1 The Six-Phase Annual Cycle
Most terrestrial plants of Théxar are synchronized with the planet's calendar: a mean 178.2 local days: six months of 29 days and four Renewal Days, five every fifth year (→ see [Volume I, Ch.34, "Systems of Measurement"]). A typical Chromophyta year consists of six phases:
| Phase | Dates | Event |
|---|---|---|
| I. Awakening | Onset of growth — Khar-Ven, Serrin-Tash | Bud opening, root growth |
| II. Vegetation | Shoot development — Thalas-Mor, Ven-Khal | Maximum shoot growth |
| III. Flowering | Formation of reproductive organs — Rass-Ur, Sha-En | Reproductive structures |
| IV. Fruiting | Ripening — Khar-Tor, The-Nur | Ripening of fruits and seeds |
| V. Shedding | Preparation for dormancy — Gharra-Vek, Mor-Irk | Leaf fall, storage of substances |
| VI. Dormancy | Dormant period — Thar-Ghal — Veks-An | Deep dormancy; timing depends on local climate |
9.4.2 Six-Layer Annual Rings
Chromophyta wood grows six rings per year — one for each phase of vegetation (→ see [Volume I, Ch.11, "Ecology"]).
| Layer | Phase | Density | Color | Information for dendrochronology |
|---|---|---|---|---|
| 1 | Awakening | Low | Light | Length of the dry season |
| 2 | Vegetation (early) | High | Dark | Abundance of precipitation |
| 3 | Vegetation (late) | Medium | Medium | Temperature |
| 4 | Flowering | High | Dark | Wind regime |
| 5 | Fruiting | Low | Light | Reserve of nutrients |
| 6 | Dormancy | Minimal | Almost white | — |
From the six-layer rings of the Mor-Ven (Tree of Time), the Keepers of the Archives reconstruct the climate of Théxar with a resolution of one vegetation phase. Continuous series reach 38,000 cycles — the longest climatic reconstruction on the planet.
9.4.3 Ephemeral Strategies of the Deserts
The annuals of the Shan Desert (genus Ash-Grass) complete their full life cycle within 6 weeks after rain. Their seeds contain a germination inhibitor that breaks down only after a second wetting at an interval of no less than 11 days — protection against "false starts" during rare isolated showers.
9.5 Unique Forms
9.5.1 Gethers — Moving Plants
The greatest sensation of the botany of Théxar remains the subclass Ghett-Chroma ("walking chromophytes") — 14 species of ephemeral grasses of the dry plains of Rhuval, capable of limited active movement.
| Parameter | Value |
|---|---|
| Speed | Slow movement as supporting roots are replaced |
| Mechanism | Directed drying-swelling of the root "foot" |
| Migration range | Up to 240 sha in a lifetime |
| Reason for movement | Following local rains |
| Population | ~2.4 billion individuals (seasonal peak) |
The movement is slow: a full "step" takes 6–9 minutes, and a movement visible to the eye requires 10–14 days of observation. The mechanics are based on the asymmetric swelling of the peripheral roots: the side facing the moistened soil elongates, dragging the plant by fractions of a sha per swelling cycle. The storage "foot" of 18–24 root lobes holds the plant in place during drought and rolls it — in essence, walks it — during the wet season.
9.5.2 Guy-Wire Lianas
The great lianas of the jungles (genus Rhu-Koss, up to 61 sha) climb the trunks of Tor-Khar without winding around them: their shoots grow vertically along "guy-wires" — their own taut fibers anchored in the host's bark. At a height of 30–60 sha the liana opens a crown that intercepts light that has not reached the lower tiers. Efficiency: a single Rhu-Koss plant intercepts up to 4.1% of the light falling on a patch of canopy, with a biomass 800 times smaller than that of the supporting tree.
9.5.3 H₂S-Filtering Epiphytes
The division Thexophyta consists of epiphytes specialized in absorbing hydrogen sulfide directly from the air (→ see [Volume VII, Ch.13, "Biosphere Interactions"]).
Xha-Ven ("the rational fern") is an epiphyte whose aerial roots form a cushion filter up to 2.4 sha across. In one cycle a single plant binds 3–6 ru of sulfur, reducing the H₂S concentration in the ground layer of the jungle within a radius of up to 40 sha by 18–26%. In the lower tiers of the jungle, where illumination is low, part of the metabolic needs is covered by the energy of H₂S oxidation — an auxiliary chemotrophic circuit duplicating photosynthesis.
9.6 Evolution of the Flora
9.6.1 Chronology
| Time (million cycles ago) | Event | Clade |
|---|---|---|
| 3,000 | First chromophyll phototrophs | Ancestors of Thalophyta |
| 1,050 | Radiation of Thalophyta | Thalophyta |
| 900 | Colonization of land (Bryoforma) | Bryoforma |
| 620 | First vascular plants (Chromophyta) | Chromophyta |
| 380 | Silicon innovation | Silophyta |
| 340 | Epiphytism | Thexophyta |
| 180 | C4-like concentrating metabolism | Chromophyta |
| 92 | Six-phase annual cycle | Tor/Thal-Chroma |
| 38 | Gethers | Ghett-Chroma |
| 0.010 | Domestication (Thex-Rice) | Khar-Chroma |
9.6.2 Driving Forces
Three main factors in the evolution of the flora of Théxar:
- Spectral pressure — the spectrum of Khar’Vex selected pigments covering precisely that region; the quantum efficiency of 0.92 is close to the theoretical limit.
- Water deficit in the dry zones under a generally warm climate — stimulated the concentrating metabolism (60% of species) and the CAM-like strategies of the Silophyta.
- Silicon availability — the excess of dissolved SiO₂ in soils and ocean (a consequence of the elevated metallicity of the crust, → see [Volume I, Ch.12, "Geological Evolution"]) made silicon biomineralization evolutionarily cheap.
9.7 Plants and Civilization
9.7.1 Agricultural Foundations
The food base of the civilization rests on six staple crops (→ see [Volume I, Ch.17, "The Flora of Théxar"]):
| Crop | Type | Share of the diet | Varieties | Yield (ru/ha) |
|---|---|---|---|---|
| Thex-Rice | Grain | 65% of calories | 210 | 4.8–7.3 |
| Khar-Grain | Grain | 12% | 92 | 3.6–5.5 |
| Mor-Bean | Legume | 9% (protein) | 41 | 2.4–4.2 |
| Tor-Fruit | Fruit | 6% | 62 | 9.1–15.2 |
| Gharra-Kelp | Marine | 4% | 24 | 18.2–30.3 |
| Khal-Nut | Oilseed | 4% (oil) | 31 | 1.8–3.0 |
Thex-Rice is a domesticated form of the wild grass of the Central Plain of Kharak, cultivated for at least 8,000 years (→ see [Volume II, Ch.02, "Early Civilization"]). It contains the full set of the 24 proteinogenic amino acids of Théxar (→ see [Volume I, Ch.04, "Biochemistry"]).
9.7.2 Forestry
| Species | Harvest rotation (cycles) | Application |
|---|---|---|
| Ven-Shar | 60 | Construction, furniture |
| Tor-Khar | 90 | Light structures, plywood |
| Needle-Bark | 45 | Sleepers, supports, paper |
| Sha-Tor | 280 | Instruments, precision technology |
The "six steps" principle (assessing the consequences six generations ahead) has been applied to logging since −600 Y.E.; since +1,300 Y.E. the felling norm has not exceeded 68% of the annual increment.
9.7.3 Pharmacopoeia
Of the ~1,200 medicinal species, the most important are:
- Khal-Ven — an antibiotic from the bark of Ven-Shar;
- Mor-Thorn — an immunomodulator from the silicon needles of the Silophyta;
- Gharra-Kelp — anticoagulants and anti-inflammatory compounds;
- Serrin-Flower — a source of membrane stabilizers, used in xenomedicine in contact with the Moryn.
9.8 Conservation of the Flora
| Indicator | Value |
|---|---|
| Protected territories with plant communities | 12% of land |
| Herbarium specimens in the Flora Archive | 2.9 million |
| Seed bank (Khar-Vexar) | 268,000 accessions |
| Extinct plant species (total in history) | 412 |
| Extinct since +2,100 Y.E. | 0 |
| Reintroduced | 23 species |
Chapter Summary
- The photosynthetic apparatus of the plants of Théxar is built on five pigments around chromophyll (570 nm); the double-sided leaf captures both incident and reflected light, and the Ther cycle protects against overheating.
- Silicon biomineralization pervades the whole flora (SiO₂ from 2% to 35% of dry mass), providing rigidity, protection, UV shielding, and vessel resistance to cavitation.
- The flora numbers 380,000 described species; 6 subclasses of Chromophyta (120,000 species) dominate the land, and Silophyta is a unique silicon division of the dry zones.
- The annual cycle of most plants is six-phase, wood grows six rings per year, giving climatic reconstructions with a resolution of one vegetation phase (series up to 38,000 cycles).
- Among the unique forms are "walking" gethers (gradually changing position), guy-wire lianas, and H₂S-filtering epiphytes binding up to 3–6 ru of sulfur per cycle.
- The evolution of the flora is driven by the spectral pressure of Khar'Vex, water deficit, and silicon availability; no plant extinctions have been recorded since +2,100 Y.E.