Exploring a massive collection of rare tropical plants | Discovery | Gardening Australia

I'm at Cairns Botanic Gardens. It's the glittering horticultural emerald, the jewel in the crown of far north Queensland, and it's literally overflown with tropical rarities, all thriving in a way that makes us from cooler climates green with envy, including me. Every year, tourists and locals alike flock to these grounds in droves to soak up some of the lush tropicana. What is the layout of the gardens? There's basically four parts to the garden. Today, we're getting a special tour of the absolute highlights. My guide is curator Dr Charles Clarke. And what is the number one destination for visitors? The cherry on top of the gardens is definitely the conservatory. And this is the cherry, the Watkins Munro Martin Conservatory. It was unveiled in September 2015. Its design used the Licawala ramseye palm leaf as its inspiration. The conservatory houses an amazing array of rare plants featuring understory tropical palms, aeroids, bromeliads, cycads, ferns, nepenthes, orchids, and a gorgeous butterfly collection. You have some fabulous foliage here. This plant is absolutely magnificent. What is it? It's beautiful, isn't it, Gerry? Yeah, this is pentagonia wendlandii. It's a rainforest understory tree from Colombia and Ecuador in South America. It's distantly related to coffee, but obviously a lot more big and spectacular and colourful than that. I have never seen the like of it anywhere. No, nor have I. Every time I visit these gardens, I pay my respects to these cycads. We've grown old together. What are they? And why are they growing in baskets? Yeah, interesting question, Gerry. They're growing in baskets because they're one of the very few epiphytic cycads. Their name is Xamia pseudoparasitica, which is a bit of a mouthful. We think these plants are over 40 years old. Wow. How far would you have to travel to see the like of these? A long way, I think. These are the only ones I'm aware of that are on public display in Australia. That's pretty amazing. It is. Pretty much everywhere I look, I see aeroids. And many of them, I have no idea what they are, but they're all looking fabulously healthy. They are. It's a great environment for them. The light's right. The humidity's right. And yeah, they just explode all year round. I don't know all of them myself. It's not a group that I specialize in. Well, here's one everybody knows. That's a peace plant. That's not a peace plant, Gerry. This is a peace plant. Wow. How old is that? Not as old as you'd think. It's probably only about three or four years old, but they grow really fast. I think every office should have one. As long as you've got a big office. If that peace plant is anything to go by, Charles and his team are doing a sterling job keeping these jungle jewels sated. This fog adds magic to this place. Why have you used it? We chose it because we wanted to imitate the environment in cloud forests and rainforests from Central America, South America and Southeast Asia. And it's the tiny drop size that we wanted to get because a lot of these places are shrouded in mist in the mornings and the afternoons. And have you noticed a difference in the plants? Do they enjoy it as much as I do? Yeah, absolutely. They love it. We're finding that they're growing a lot faster, they're getting fewer diseases, and we're using a lot less water in the process. Of all the aeroids, the genus Amorphophallus is one of the most talked about, and this collection is home to around 50 odd species. They're bizarre, they look like triffids, they smell incredible. Yeah, there's a lot to like about them. Now, one of the other names for these is corpse flower. The most famous Amorphophallus of all, the Titanarum, Amorphophallus titanum, has this reputation for smelling like a dead animal. Now, I can smell various odours here. This one down here smells a bit like natural gas, and then there's a smell of slightly off fish wafting to me. Why do they do that? We think it's to assist with pollination, because the main pollinators are carrion flies, and they are very sensitive to the smells of rotting flesh. And a lot of these plants, when they're in their natural habitats, are situated quite a long way from each other. So by producing a chemical that will attract a pollinator that flies a long way, they're able to affect pollination over large distances. Now, the flowers also warm up. They do. They're what's called thermogenic flowers, or thermogenic inflorescences, because the flowers are actually very small on these. And at the right time during the flowering cycle, if you put your finger inside, you can actually feel the heat coming off the inflorescence. Fascinating. Charles readily admits to not knowing the origins of every species here. Some, quite simply, remain mysteries. I love my bat plant, but I've never seen anything like this. Nor have we, to be honest. It sort of exists in the nursery, and every now and then, it throws up an incredible-looking flower like this. But this is absolutely bizarre. It really is, yeah. Only in a botanic garden, eh? Yep, absolutely. This eclectic collection is fascinating, ranging from the very tall to the very small, including this hidden gem. This is a ginger from Peninsular Malaysia called Zinjiba malayanum, variety Midnight. And it's notable for its bright yellow flowers when it's young, and as those flowers age, they turn to a hot pink colour. It's a rainforest species. It likes the tropics, but it's also reasonably hardy, so you can grow it with a little bit of care further south in Australia. You are literally surrounded by botanical riches. Do you have any favourites? I do, Gerry. I've probably got about 100 favourites in this garden, but this one would be my favourite of the favourites. This is called Impatiens mirabilis, and it's basically a giant busy lizzie. Many gardeners will be familiar with busy lizzies, but this really looks like it comes from a different planet. It does. It looks like a baobab. It's almost like a tree with its fat trunk and its big, chunky, fat branches. It's actually a species that grows on limestone cliffs in southern Thailand and Peninsular Malaysia, where it grows almost straight out from the surface of the cliffs, and then its branches tend to bend up. This one's growing in the ground, so instead of bending around, it's just gone straight up. Wow. That's a stunning plant. Yeah, it's really cool, isn't it? Charles, I've been coming to these gardens for almost 40 years, and every visit, they get better and there's more to see. Yeah, we're always trying to make things a bit different, trying to improve beds and try and improve the flavour and appearance of the garden, so it's an ongoing job, but it's a very exciting and interesting one, too. Well, it's a cracking place, and it's a must-see destination. Thanks, and it's all due to the efforts of our staff, who are very dedicated, very professional, and give a great deal to make the gardens look the way they do.