Is this plant safe?

I recently purchased some Lobelia cardinalis for my community tank. It's growing like crazy and I'm sure is putting on 2-3cm a day. It'll be reaching the surface soon — and this is where my question comes in. I'm given to understand that this plant is toxic (although not to fish it seems), and particularly in its emerse form. If it does eventually emerge from the surface, is it likely to flower? And if so, is there a risk from any flowers or leaves that drop into the water — or, considering I have pets, anywhere outside the tank? I'd love for it to flower, as it would look amazing, but should I prune the plants back to stop this, just in case? ADAM PARKER, VIA EMAIL

JORDAN REPLIES: Lobelia cardinalis is said to be toxic to both humans and pets, such as dogs and cats, if consumed in large quantities. The toxic alkaloid found in all Lobelia species is called lobeline. Although all parts of this plant are poisonous, it is safe to handle.

I have grown this plant both emersed and submerged for extended periods of time and never experienced any flowers. This is likely due to this plant taking approximately two years to fully establish and grow into its adult form. Once mature it will reach heights between 60-120cm. After the plant blooms it will drop seeds for the next season. If you still want an emersed plant to flower with an equally striking, or debatably more striking, appearance, consider

Pogostemon erectus. This stem plant is often used in its submerged form but once it breaks the water surface it creates wonderful purple candleshaped flowers.

It’s worth mentioning that many popular house plants are also toxic to mammals, but if we have no intention of eating these plants, then there’s no danger.