Glossostigma Elatinoides - Portion Cup

Glossostigma Elatinoides is the carpeting plant that built the modern aquascape, and it remains one of the finest looking and least forgiving. Tiny paired round leaves on creeping runners form a bright green lawn barely half an inch tall when it is happy. The word "happy" is doing real work in that sentence: glosso wants strong light and CO2, and without both it abandons the carpet and grows straight up instead. Get the conditions right and nothing else looks quite like it. See the rest of our live freshwater plants for gentler options.

Care Guide

• High light is not optional. This is the whole game. Under insufficient light glosso turns vertical, stretching upward with bare stems and spaced leaves instead of creeping sideways. If yours starts climbing, the light is too weak or something is shading it.
• CO2 is strongly recommended. Pressurized injection is the reliable path. Seachem Flourish Excel can carry a low tech attempt, but be realistic: without carbon supplementation glosso rarely carpets properly.
• Substrate and fertilizer: a rich planted substrate like CaribSea Eco-Complete, plus regular water column dosing with Seachem Flourish. A hungry carpet is a thin carpet.
• Planting technique matters. Separate the portion into very small clumps of two or three plantlets and push each one into the substrate about an inch apart. Planting it as one lump gives you one lump; spacing it out is what produces an even lawn.
• Water: 68 to 78°F, pH 6.0 to 7.5. It prefers the cooler half of the tropical range.
• Trim it. Once established, glosso grows in layers and the lower ones die back if you let it get thick. Mow the carpet with scissors every few weeks and remove the clippings.
• Your portion cup is tissue-cultured or emersed stock. Rinse any gel or rockwool off the roots before planting, and expect a transition period as the submersed leaves come in.

Specifications

Placement and Companions

Where it goes: foreground only, in the brightest open part of the tank. Never plant it where hardscape or a tall plant will shade it later, because shade is the one thing that reliably ruins it.

Carpet alternatives if this is too demanding. Monte Carlo gives a very similar look with far more tolerance for moderate light and no CO2, and Dwarf Baby Tears is finer but similarly demanding. If you are not running high light, buy the Monte Carlo instead. We would rather sell you the plant that lives.

Texture partners: behind the carpet, Staurogyne 'Porto Velho' or Dwarf Hairgrass step the height up gradually without blocking light.

Fish and invertebrates: safe with community fish and shrimp. Avoid substrate-digging cichlids and large goldfish, which will uproot a fresh carpet before it anchors. Corydoras and small loaches are fine once it has rooted in.

Recommended Supplies

• CaribSea Eco-Complete: the nutrient-rich substrate a carpet needs to root into.
• Seachem Flourish Excel: liquid carbon, the minimum carbon source if you are not injecting CO2.
• Seachem Flourish: comprehensive water column fertilizer for daily demand.
• Seachem Flourish Tabs: root tabs to enrich plain gravel under the carpet.
• Monte Carlo: the forgiving substitute, if your tank is not high light.

FAQ

Why is my glosso growing straight up instead of sideways?
Not enough light reaching the substrate. That vertical stretch is the plant hunting for light, and it is the single most common failure. More light, or less shading from plants and hardscape above it, is the only fix.

Can I grow it without CO2?
Some people manage it under very strong light with liquid carbon and disciplined dosing, but it is genuinely difficult and the carpet stays thin. If you have no CO2, Monte Carlo gives you close to the same look with a fraction of the trouble.

How should I plant the portion cup?
Split it into small clumps of two or three plantlets and plant each one about an inch apart across the area you want covered. Tweezers help. Spacing is what turns one cup into a lawn.

How fast does it carpet?
Under high light and CO2, a few weeks. Under anything less, it may never close up properly. Glosso is fast when conditions are right and stalled when they are not, with very little middle ground.