Cucumis metuliferus, Cucurbitaceae

Each year I try to grow something a little bit unusual that's also edible and this year it was the turn of this weird fruit, the African horned melon Cucumis metuliferus. The plant resembled a small-leaved melon that rambled across the greenhouse staging, producing numerous small unisexual yellow flowers. Whenever a female flower appeared I carefully pollinated it but none seemed to be setting any fruit. It was only when I had given up and was about to throw the plant away that I parted the leaves and found this fruit, about 12cm. long and looking like something from another planet, revealing that one pollination had been successful. It looks like a vegetable version of a medieval mace and would probably make a good weapon, because those spines on the tips of the horns are very hard and sharp.

So, what does it taste like? Rather like cucumber, but with lemon juice added - quite refreshing - but the texture is strange. Each seed is surrounded by a semi-solid gelatinous coating and in the mouth it feels rather like eating frog spawn (not that I've actually eaten frog spawn, but this is what it must be like). Definitely an acquired taste. I spat out the seeds and will sow some next year, to see if it's any better second time around.

The plant is a native of Africa, although I gather that it's now cultivated in several countries and is known as kiwano on the US West Coast.

Bitter Gourd, Momordica charantia

Bitter Gourd Momordica charantia has to be one of the most memorable plants for a conservatory that I've grown in recent years. Once germinated the seedlings grow very quickly and need to be trained up a support (a wig-wam of canes works very well), which they tie themselves to very efficiently with their tendrils. Then they produce large numbers of yellow flowers. These are nothing special to look at - rather like cucumber flowers - but like many members of the cucumber family the plants are dioecious, producing separate male and female flowers on the same plant, so you have to pollinate them by hand to be sure of good fruit set on the female flowers..... but it's worth the effort. They quickly produce what look like small, warty cucumbers that are 15-20 cm. long  which ripen to a vivid shade of yellow then suddenly split open at the tip to reveal seeds covered with a sticky scarlet aril (an extra seed coat). The fruit is edible if cooked (but they're not called bitter gourds for nothing!) and they have a long history of use in Ayurvedic medicine . For that reason the plant is widely grown in India, although no one seems sure exactly where it originally came from. There is also some recent reputable research that suggests that the plant's chemical constituents may be of value in the treatment of diabetes. It's widely grown throughout the tropics, from Africa to the West Indies.

Queen Anne's Pocket Melon, Cucumis melo

This is the wild form of melon Cucumis melo known as Queen Anne's pocket melon. It's about the size of a snooker ball and grows as a weed in melon fields in the US. It's edible but insipid. The main reason for growing it, apart from its ornamental properties, is its incredibly intense melon fragrance. One ripe fruit, which lasts for about ten days before it goes soft, will perfume a whole room. Apparently Victorian ladies used to carry them around in their pockets, as a kind of portable pomander. I've grown it for a few years and found that it looks particularly striking in a hanging basket in the conservatory, where the fruits can dangle down like striped orbiting planets. The plants are quite compact and carry separate male and female flowers, so it pays to deliberately pollinate the female flowers to ensure fruit set. Each plant generally produces about half a dozen fruits. The seeds are hard to come by (I got mine via an exchange with a Dutch botanic garden) but I see from a quick Google search that there are a few suppliers in the US.