Yellow rattle rhinanthus minor
Table of Contents
Yellow rattle takes its name from the colour of its ‘tube like’ flowers and the sound made from the seed rattling in the ripened seed pods. A useful plant to sow in wildflower meadows as it helps supress unwanted coarse grasses.
Plant family: Orobanchaceae
Aliases: Bays rattle, corn rattle, cockscomb, hay rattle, little yellow rattle, pots and pans, rattle baskets, rattle grass
Flowering period: May – July
Flower colour: Yellow
Preferred soil type: Infertile
Habitat: Grassland, meadows, dunes
Status: Common
General information
A relatively low-growing plant (up to 50 cm tall) and an attractive, hemi parasitic, annual wildflower that’s very beneficial to wildflower meadows and sometimes referred to as ‘meadow maker’. The roots of yellow rattle attach themselves to roots of other plants, especially unwanted coarse and meadow grasses that out compete the desired wildflowers. It doesn’t make the grass appear less healthy, it just weakens it.
Once attached, they draw valuable nutrients from the grasses, thus weakening them, reducing the competition, allowing the wildflowers to flourish and produce more floral diversity. As you would expect yellow rattle is considered a troublesome weed for farmers, as its presence can reduce hay yields of up to 50% and it’s an annual its relatively easy for farmers to eradicate.
Sowing & Establishment
Seeding is the preferred method for growing yellow rattle, although plug plants can be purchased, but end up being rather expensive (especially for large areas) as they have to be grown with grass. Sowing and the establishment of yellow rattle can be a bit hit and miss, with varying results from year to year and it can take 2 or 3 seasons to establish an acceptable amount.
As yellow rattle seeds have a short life span (up to 18 months), it must be sown when the seed has been recently harvested from the current season and should be sourced from a reputable supplier. The wind-bourne seed needs to be carefully processed, as they quite fine & delicate and any damage to them will result in poor germination.
Another option is to collect the seed from the plant itself. Perhaps you know someone or you could contact a nature reserve, asking their permission to gather some seed heads once the plant has set seed (usually between June and August). Simply remove the stems with the seed heads and shake the seed into a bag, only a few are required per square yard.
In order to give the seed the best chance to germinate and establish, the seedbed needs to be prepared correctly. The optimum time for sowing the seed is during the autumn, but no later than December. The reason for this is the seed requires a period of prolonged cold weather before it will germinate (a process known as vernalization).
Ideally the seed should be sown into the existing grassland or wildflower meadow. The first task is to mow the area as short as possible (below 25mm), even scalp it, removing all of the clippings in the process.
The next stage is to rake or chain harrow for larger areas, to remove as much dead material (organic matter or thatch) as possible and to expose the bare soil. Aim for a minimum of 50% soil exposure as this helps the seed come into contact with the soil and increases the chances of germination and establishment.
Sow the seed by hand or by spreader. Mixing it with an inert carrier, such as sand will help bulk up the mixture and help with the application as the sowing rate is very low at 0.5 – 1 grams per square metre. If sowing into a new meadow the seed can be mixed with the intended mixture, again bulking up with sand if necessary, for easy application.
As the seed is very expensive, it’s an option to just sow selected areas and if successful the yellow rattle will eventually spread to the other areas on the site naturally.
Finally the area will require treading or rolling to help the new seed come into contact with the soil, finally give it a thorough watering. At this time of the year and with winter on the way it’s unlikely that little, if any more irrigation will be required.
The following spring (late Feb – early March) look for the first signs of yellow rattle seedlings and once they appear avoid mowing the area, as if the heads are knocked off the young plants it will be the end of them. Don’t be disappointed it only a few plants germinate in the first year, as with the correct management they will increase in subsequent years.
The yellow flowers bloom for around a month (peaking in June), before the seed pods turn brown and ripen and can be heard rattling in the breeze ( hence the name). The plant then drops its seed and you are free to go ahead and mow the meadow if you choose to do so.
However, you may want to wait before mowing, as there may be other late flowering wildflowers that need to drop their seed. It is important to remove the clippings and keep it mown short until the growth has dropped off.
In some situations the establishment of yellow rattle may prove quite difficult. This wildflower thrives in poor under nourished soils and may struggle to establish in rich nutritious soils and sites with aggressive coarse grass such as perennial rye grass, which are too much for yellow rattle to be effective. It will also suffer in shaded sites or where the grass or other vegetation is too long and block out the sunlight (which is required for yellow rattle to thrive).
Identification
Flowers: The 2-lipped yellow tube-like flowers emerge from a pale green, inflated calyx, measuring between 12 – 15mm long. The upper lips have 2 small violet tips – teeth.
Leaves: The leaves are opposite, hair-less with a glossy surface and prominent deep green veins, oblong to linier-lanceolate in shape with rounded or toothed margins, measuring between 5 – 15mm across.
Value for wildlife
Yellow rattle produces a valuable source of nectar for many types of bee, butterflies, hoverflies and moths.
Yellow rattle images
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