Herzblatt – ingredients, effect and application

Heart leaf (Hoya kerrii) is popular in this country as a houseplant because of its thick leaves, whose shape is reminiscent of a heart. These leaves serve as water storage for the succulent. In their countries of origin, the species of the genus Hoya are used in ethnomedicine as a remedy against inflammatory diseases.

Characteristics

• Scientific name: Hoya kerrii
• Common Names: Heart Plant, Little Darling, Wax Flower, Porcelain Flower
• Family: Dogpoison family (Apocynaceae)
• Distribution: East Asia from China to Japan, Cambodia, Vietnam, Laos, Thailand and Java
• Plant parts used: leaves, shoots
• Ingredients: Triterpenes (especially luteol), glucosides, palmitate (salts and esters of palmitic acid)
• Areas of application: In the countries of origin, preparations with Hoya species are used against inflammatory diseases.

Herzblatt – An overview

• The heart-shaped leaves make the plant a symbol of love, and in this country the cuttings are given as gifts especially on Valentine’s Day, Christmas and birthdays.
• Hoya kerrii grows enormously and herbaceously, depending on the location it becomes a climbing or hanging plant.
• The leaves contain triterpenes, which have an anti-inflammatory effect.
• The sap is mildly toxic, which poses little risk to adults but can be problematic for small pets and young children.
• Studies are underway to analyze the effects of certain ingredients on the pancreas and potentially use them in anti-diabetes medications.
• Heart leaf needs a lot of air humidity, but little moisture in the soil, a bright location but protection from direct sun.
• Hoya is easy to propagate through leaf cuttings.

Heart leaf – ingredients

Heart leaf contains triterpenes (especially luteol), glucosides, palmitate (salts and esters of palmitic acid). Some of these esters are found exclusively in Hoya kerrii and related species of the dogpoison family.

Medical effects

A 2017 study isolated several glucosides from the plant that have been shown to inhibit inflammatory processes. Another study published in 2018 mentioned that among various triterpenes isolated from Hoya kerrii, lupeol is known to have strong anti-inflammatory effects.

According to a 2020 study, there is evidence that Hoya kerrii extract influences processes that slow down certain forms of cancer and diabetes. In addition, heart leaf has not only been used for a long time in folk medicine against inflammatory diseases, but is also important for today’s medicine.

How poisonous is Hoya kerrii?

Hoya species are slightly poisonous. Acute toxicity studies are necessary to ensure their safety for pharmaceutical products.

In addition, studies are needed to determine the chronic toxic effects of long-term use of preparations containing Hoya. In addition, studies must be carried out to rule out the possibility that Hoya products have a negative effect on the fetus in the womb.

Is there a danger with heart leaf as a houseplant?

There is probably little or no risk to adults with Hoya as houseplants: touching, transplanting or otherwise coming into contact with heartleaf shoots does not cause poisoning (according to current research).

However, a certain risk cannot be ruled out for small children and pets. The thick, fleshy leaves of succulents can entice children to playfully consume the plant.

Since the toxin is mainly found in the milky sap within the leaves, consumption can cause poisoning in children. Danger to life is very unlikely.

However, symptoms can occur. These include painful gastrointestinal complaints, nausea and vomiting and diarrhea.

What characterizes Hoya kerrii?

The heart-shaped leaves that give it its name are typical of Hoya kerrii. These grow on long shoots, which climb up to four meters in length.

The star-shaped flowers in spring are white with a red spot in the center. Their consistency is reminiscent of wax. This gave the group the name “Wax Flowers”.

The beautiful flowers of the heart leaf earned the plant the nicknames “wax flower” and “porcelain flower”. (Image: GooRoo/stock.adobe.com)

How much water does the heart leaf need?

Hoya kerrii is a succulent plant and is adapted to longer dry periods thanks to its water-storing leaves. That’s why you only have to water the plant rarely: too much water is more harmful than too little liquid.

As a rule of thumb, you should allow the substrate to dry completely between each watering. Waterlogging is dangerous for Hoya kerrii, and the roots are sensitive to it.

In its natural habitat, Hoya kerrii grows in locations that have little soil moisture. However, air saturated with moisture.

Spray heart leaf

That’s why you only have to water the heart leaf rarely, but spray it regularly. You can use a spray gun or an electric humidifier for this.

Alternatively, you can place a bowl of water next to the plant. The evaporating water then benefits the plant.

The following is important: Hoya kerrii tolerates lime poorly. Rainwater is best suited for watering and spraying. If you use tap water, you should filter it.

Hoya kerry pflanzen

Heart leaf plants are usually purchased as potted saplings. It is best to repot commercially available plants immediately, as the substrate is usually not optimal and the pot is too small.

So you pot the heart leaf in a larger container, add the appropriate substrate and set up drainage to prevent waterlogging. To do this, mix pottery shards and/or gravel as a soil layer, place a fleece over it and sprinkle the earth on the fabric.

The aerial roots must remain free. Ingrown heart leaves need little moisture. However, when planting, you should water the substrate so well that everything is watered.

This is necessary so that the substrate binds together and the roots grow in. You can pour off the collecting plate to prevent waterlogging from forming there.

What kind of soil does Hoya kerrii need?

Hoya needs a permeable substrate that absorbs air. Pure potting soil is not suitable for this because it is too dense.

You can loosen potting soil with coconut fibers or use orchid soil. Tropical orchids prefer a similar ground to Hoya in their natural habitat.

Hoya also gratefully accepts hydroponics. Instead of coconut fiber, you can also use one third potting soil, one third pine soil and one third lava granules.

Does Hoya kerrii need fertilizer?

Hoya doesn’t need a lot of fertilizer, but occasionally it does, because the irrigation water washes nutrients out of the soil. Liquid fertilizer for houseplants, which you add to the water every three weeks, is ideal for this purpose.

What location does the plant need?

Herzblatt requires a special location. The plant needs a lot of light, but is sensitive to direct sunlight.

It also needs high humidity. An ideal place for a hoya plant is a bright bathroom where humidity and light are guaranteed.

The heart leaf can remain outdoors between the end of May and the end of August. Here it should be on the east or west side: in the south the sun shines too directly, in the north the light is too low.

In the apartment, Hoya should not be placed directly next to a turned on heater and should not be exposed to drafts from an open window. Heart leaf is a climbing plant and needs a lot of upward space.

As a hanging plant, it bulges down with a lot of space. For example, it is suitable as a hanging plant on a wall shelf high in the room or on a cupboard.

Heart leaf does not tolerate frost. In the cold season, temperatures between ten and 15 degrees Celsius are good. Since Hoya is now dormant, it only needs to be watered sporadically.

Which pests attack the heart leaf?

The most common pests that affect heartleaf plants include spider mites and lice. More specifically, scale insects, mealybugs and aphids.

Such ectoparasites like succulents because they store fluid and thus provide the plant sap that the mites and lice feed on. This causes the plants to dry out over time, become crippled and die.

How can sweetheart leaf be propagated?

Adult Hoya are easily propagated by cuttings. To do this, a leaf is broken off the stem, which requires little effort and does not harm the heart leaf.

You let the break point dry for a day and then put the leaf in moist heart leaf substrate in a bright place. In a few weeks the leaf will root in the soil.

Is the heart leaf cut?

Even if heart leaf forms long tendrils, it is better not to cut it. Instead, offer the plant something to help it climb. (Dr Utz Anhalt)