The arrowhead (Sagittaria sagittifolia) is a popular aquatic and marsh bedding plant. The perennial is especially popular as a specimen plant in the shallow water zone of a garden pond or other artificial water feature.
The attractive species is considered to be easy to care for and reproduces quickly. In addition, it also works very well as a natural filter.
Origin and Distribution
Like the various species of the related Alisma (Alisma), the arrowhead (Sagittaria sagittifolia) belongs to the water-plantain family (Alismataceae).
The species is widespread mainly in the stagnant to calm-flowing, calcareous and nutrient-rich waters of the North German Plain.
But it also occurs in the rest of Central Europe as far as the foothills of the Caucasus. It is even known in Siberia and as a neophyte in North America.
The perennial prefers flat regions. You will not find it at altitudes above 1,640 ft ( 500 m).
Use
The hardy arrowhead is planted in the garden mainly as a low-maintenance ornamental plant in the shallow water zone of a garden pond and other shallow water areas.
It is especially valuable as a so-called repositioning plant. These are plant species that filter the water in a completely natural way. Thus, they can keep it healthy without chemical additives.
You can very well plant the arrowhead as a solitary. But it also works in small tufts of no more than eight plants per 10 sqft.
In addition, there are a number of suitable planting partners such as purple loosestrife (Lythrum), dwarf bulrush (Typha minima), or hard rush (Juncus inflexus).
Furthermore, the arrowhead also harmonizes very well with species such as the floating heart (Nymphoides peltata) or various water lilies (Nymphaea).
Appearance and Growth
This perennial aquatic plant grows in a densely caespitose manner, forming numerous stolons over time.
Due to the strong leaves growing above the water surface, the arrowhead reaches growth heights between 12 and 20 inches (30 and 50 cm).
The plant retracts the above-ground parts before winter and overwinters in the form of spherical tubers at the bottom of the water. It forms these overwintering tubers on its stolons.
If the plant is in a sunny location, it will always orient its leaves in a north-south direction. This behavior is to protect the leaves from the sun.
Moreover, you can use it as a natural compass. For this reason, some people refer to the arrowhead as a “compass plant”.
Leaves
In principle, the arrowhead forms three different types of leaves, each with a different shape.
For example, the floating leaves, which are always submerged, are ribbon-shaped and are formed first.
Only then follow the first, oval to broadly shaped leaves above the water surface. These are visually very reminiscent of those of the related water plantain.
At the very end, the eponymous arrow-shaped leaves follow, which make the species so distinctive. The leaves, which stick upright in the air, are long-stalked and triangular.
In autumn the deciduous leaves turn yellow.
Flowers and Flowering Time
The white flowers of the arrowhead, only about 1 to 2 inches (2 to 4 cm) in size, appear between June and August.
They consist of three petals arranged in tiered whorls on long, triangular flower stalks and have a pink center.
The female flowers are located on the lower whorls, the larger, male flowers on the upper whorls. Pollination is usually by hoverflies, but also by other insects.
Fruits
Following flowering, inconspicuous, small nut fruits develop. These contain only one winged seed each.
Is the Arrowhead Poisonous?
The arrowhead is not poisonous. In fact, the tubers found on the stolons of the plant are actually edible. This is why the species is cultivated for consumption primarily in China as well as other Asian countries.
The starch-rich tubers have a taste reminiscent of potatoes. You should peel them after preparation, however, because the skin contains many bitter substances.
Arrowhead root tubers are especially commonly cooked and made into flour, which is suitable for both cooking and baking.
Not all species of arrowhead develop edible tubers, though.
If you are interested in exotic vegetables, try water caltrops (Trapa natans). This also spreads extensively on larger garden ponds.
Sometimes people mistakenly call the water caltrop water chestnut. But water chestnuts are actually Eleocharis dulcis.
Which Location is Suitable for Arrowhead?
The adaptable and extremely robust arrowhead needs a sunny to semi-shady spot on the bank of a standing or slow-flowing body of water, such as a garden pond or a stream.
Here you should plant it on the bank to depths of no more than 16 inches (40 cm). In addition, the body of water should have a high nutrient content so that the plant can thrive in it.
Soil
A permanently wet, humus-rich, and loamy or muddy substrate is ideal. In this, you plant the arrowhead at a water depth of between 2 and 12 inches (5 and 30 cm).
Because of the various foliage found both below and above the water surface, the species copes quite well with fluctuating water levels.
Planting Arrowhead Properly
When planting, place the bulbs of arrowhead directly into the shallow water area of the garden pond and cover them with gravel. In this way, you will prevent it from washing away.
For a group planting, you should plant no more than about six to eight specimens per 10 sqft.
For a solitary planting as well as in smaller garden ponds, on the other hand, it is advisable to plant the tubers in special planting baskets to counteract spreading from the outset.
The best season for planting the attractive aquatic plant is spring.
Watering and Fertilizing Arrowhead
Maintenance measures such as watering and fertilizing are not necessary for planted arrowhead, provided that the nutrient content in the water is correct.
Pruning Arrowhead Properly
Pruning measures are also unnecessary. Only the parts of the plant that turn yellow in the fall should be fished off the water surface before winter, but you should not cut them off.
The tubers draw the nutrients they need for new shoots in spring from the stems and foliage, so removing these prematurely will lead to a nutrient deficiency. As a result, the arrowhead will no longer sprout.
Propagating Arrowhead
Arrowhead often needs to be prevented from spreading excessively when it is planted, as the species is extremely prolific. For this reason, it also appears on state noxious weed lists for 46 states in the US.
The arrowhead reproduces all by itself both by self-seeding and by its overwintering tubers, which develop on the numerous stolons.
However, you can also propagate the plant specifically by dividing it, digging it up along with its rootstock, and cutting it into the desired number of divisions. Each section should have at least one sprout.
Then, you can replant it in a new location. It is best to divide the plant in spring when the signs are pointing to new shoots anyway.
In addition, you can – also in spring – separate the overwintering tubers from the mother plant and also plant them out separately in a new location.
Wintering Arrowhead
Special overwintering measures are not necessary, since the arrowhead is sufficiently hardy.
It retracts its foliage in the fall and stores the nutrients therein in the tubers, which form on the stolons over the summer and eventually sink to the bottom of the water.
In the spring, the plant resprouts from these tubers.
Diseases and Pests
Basically, the arrowhead is unproblematic with regard to diseases and pests and is resistant to both.
The only problem, especially on larger ponds, can be hungry ducks, which also find the starchy tubers very tasty and eat away entire stands practically overnight.
Species and Varieties
Botanists distinguish about 40 different species of the genus arrowhead, which are native to both the climatic temperate to tropical regions of the earth.
Depending on their origin, you can use the various arrowhead species for planting artificially created water bodies in the home garden or also in aquariums.
In contrast to the arrowhead Sagittaria sagittifolia, the varieties originating from tropical regions are not hardy. The genus Sagittaria belongs to the plant family of the water-plantains (Alismataceae).
Broadleaf Arrowhead (Sagittaria Latifolia).
Native from Canada to Mexico, this species is also known as duck-potato, Katniss, and wapato.
This hardy, upright-growing perennial develops strikingly broad, arrow-shaped, glossy green leaves. It reaches growth heights of between 16 and 24 inches (40 and 60 cm) and displays pretty white, slightly pink-tinged flower panicles between June and August.
You can place the plant in water up to 16 inches (40 cm) deep. It overwinters with the help of its so-called overwintering tubers. But beware: these are eaten with preference by ducks.
Grassy Arrowhead (Sagittaria Graminea)
This species also originates from Canada as well as the USA and is well tolerant of frost.
The perennial’s medium green foliage leaves are lance-shaped and narrower than those of the other arrowhead species. The plant grows to about 16 inches (40 cm) tall.
You can cultivate this species in containers as well as by or in a garden pond or other man-made body of water. The pretty white flowers appear between June and September.
Awl-Leaved Arrowhead (Sagittaria Subulata).
Also known as narrow-leaved arrowhead or dwarf arrowhead, this species is native to the warm regions of the southern United States and West Java.
The aquatic plant grows up to 24 inches (60 cm) high and is not hardy, but is a popular ornamental plant in aquariums. It is considered easy to care for and is therefore also well suited for beginners.
Unlike specimens planted out in garden ponds and other bodies of water, you should regularly fertilize arrowhead cultivated in aquariums as the plants have a high nutrient requirement.
