The Biology of 3 Native Edible Plants - PawPaw - Passionflower - Pecan
Top Left - PawPaw Thicket with Wingstem. Top Right - Large Sliced Pawpaw Fruit. Bottom Left PawPaw Fruit. Bottom Right - Open Grown Tree 20 feet tall.
This short article was written by Solomon Gamboa; Author of Native Meadowscaping , Native Plant Agriculture , and A Native Plant Propagation Guide & Nursery Model all available at this link.
Pawpaws (Asimina triloba) require a moderately amount of soil moisture to be highly productive. In a soil high in clay or sand content, Pawpaw can establish but will do so in a stunted manner especially if it’s competing with older tree roots and thick herbaceous plant growth for water. Climax Pawpaw production is within silty alluvial soiled bottomlands or floodplains parallel with rivers, silty rich and deep bedrock soils (residuum) or on glacial outwash soils of the glaciated regions in the U.S. They are a generalist as far as PH of soil, able to grow in PH as low as the upper 4 range and as high as +8 PH. Try to keep pawpaw production on slopes of less than 10%. Of they are to be on steeper slopes, choose a slope that faces East, North East, North, or Northwest where the soil temperature will be cooler during the summer. Pawpaws grow best on flatter topography. They’re fully tolerant of saturated winter soils that occur in seasonally high water table soils. These type of soils are found in neighborhoods within which most houses don’t have basements due to the flat poorly drained topography.
In forests, PawPaws establish as small understory trees that create suckers that await the falling of a canopy tree. Once a Canopy tree has fall, the PawPaws accelerate their growth rate to temporarily dominate the mid story within the canopy opening. This is when they become fruitful in forests. In open conditions, PawPaws can become fruitful in as little as 5 years from planting. If you want a fast growing PawPaw in your landscape, do it the favor of providing 3 to 4 inches of water per month during the summer months in the case of drought. Mowing around Pawpaws prevents it from suckering into colonies, forming single trees. Suckers cannot cross pollinate each other and create fruit. You need two pawpaws born from two different seedlings (genetically distinct) to cross pollinate and create fruit. If you’re dealing with cultivars, you need two different cultivars for fruit.
Germination Tips: Extract the seeds from the fruits. Place the seeds in a pot full of silty soil (not clayey or sandy). Leave this pot outdoors all fall and winter - buried halfway underground so it is not subjected to the coldest temperatures. In early spring, strain the silty soil from the seeds by using a hose on a jet setting and a strainer; washing the silty soil away leaving only the seeds. Sow in early spring and expect germination by mid Summer. Grow the seedings in full-sun or partial shade (either). Full-sun for the seedlings will result in larger seedlings than those grown in partial shade.
The Zebra Swallowtail is one of the better known insects whose larval form host on PawPaw (bottom). Sapsuckers maintain holes (top) in Pawpaws and other species to utilize the sap. They also consume native insects that are attracted to the sap holes and that are found elsewhere.
(This native Passionflower is being perfectly pollinated by a Carpenter Bee species (Xylocopa sp.) Resulting Fruit pictured in the bottom right.
This native Passionflower (Passiflora incarnata) is a rhizomatous native vine that offers medicinal, edible, fragrant, aesthetic, and pollinator attractive qualities. When ripe the fruits’ insides will be full of juicy translucent pulp sacs that contain flat black seeds. The pulp sacs are designed to be swallowed whole by mammals with the seeds inside, so that the seeds pass through the digestive system and are deposited elsewhere. The pulp tastes like a tropical-fruit version of Capri Sun and its used to flavor ice cream, sorbet, sherbet, candy, and drinks. Passionflower naturally grows in sunny environments within native prairies, human-made fields and wood edges, and natural edges such as wetland edges, edges of thickets, and riverbanks. They are strongly rhizomatous, meaning they will pop up clones of themselves through underground stems known as rhizomes. For this reason they are best cultivated on fence lines or provided with a welded wire fence to climb, surrounding by lawn in its own bed. The mowing around the Passionflower will contain its suckering and help to keep it one place. You must plant two passionflowers born from two different seeds (genetically distinct - non-clones) to get passionflower fruit. This passionflower species is not too shade tolerant, but it’s not picky about Soil PH.
Carpenter Bee Partners (Pictured Above)
See how the carpenter bee fits perfectly between the anther (pollen releasing part of the flower), and the flower petals it stands on. As it pushes its way to the center of the flower, which holds nectar for the Carpenter Bee, the hairs behind the head get rubbed on the underside of the passionflower's anthers which in turn are dumping golden pollen onto the bee. Passionflower is in part interdependent or symbiotic with these large carpenter bees whom have a big appetite for their nectar.
Germination Tips: There are a couple of keys to getting high Passionflower germination. 1. preferably do not let them dry out if you’re able to collect them in person. If you’re buying passionflower seeds, they will be dry. To help rehydrate them, soak them in water for 5 days. The water will slowly re-saturate the seed. The cold-moist stratify them for at least 90 days or leave them in a pot outdoors all fall and winter, halfway buried underground to protect from the coldest temperatures. Sow 1/4th inch beneath the surface in the spring time. They will germinate when air temperatures consistently reach above 77 degrees.
(The Gulf Fritillary (Agraulis vanillae - left) and the Zebra Longing (Heliconius charithonia - right) caterpillars require different species of passionflower as a host plant. Both species have formidable spikes as caterpillars combined with bright colors to warn predators that they may be poisonous.
Pecan in a field, ripe pecan nuts, and a resident of Pecan trees - a Screech owl. The owl likely hunts rodents who are attracted to the pecans when the pecans begin ripening.
Pecans (Carya illinoinensis) are already well rooted in U.S. food culture. In some southern states, 30-60% of the pecan production are wild-harvested, though Native Plant Agriculture plans for the agricultural expansion of pecans; not more intensive wild-harvesting. Being a native hickory tree, they can host over 200 butterfly/moth caterpillars as well as many of other native insects. They naturally range as far north as the Illinois/Wisconsin/Iowa tri-state. When seedlings are grown from northern populations; they bear well throughout the lower midwest and mid-atlantic states (Zone 6 and much Zone 5). Pecans can attain massive size; larger than all other hickories especially when planted in bottomland or floodplain soils. They are PH Generalists, adapted to PH in the 5 to 8+ range. Their massive root systems, like that of an Oak’s, afford them good drought tolerance throughout their native range. This is the fastest growing Hickory of all trees within the Carya genus.
Germination Tips: If you’re luck enough to have found a fruiting hickory tree, create a mouse proof container. This is typically a container with drainage holes that is covered with zip-tied hardware cloth. Place the Pecans in soil within this mouse-proofed container, and bury it +85% underground. Unearth it in the spring time and sow the Pecans in full-sun. They’ll need air temperatures to consistently reach about 77 degrees before they will germinate in mass.
Pecans host many types of insects, including caterpillars (moths and butterfly larva) like the Hickory Horned Devil (Citheronia regalis, top left), Hickory Tiger Moth (Lophocampa caryae, bottom right), Red-humped Caterpillar (Schizura concinna - top right), and the Luna moth (Actias luna - bottom left). All of these caterpillars are have widespread ranges in the eastern U.S. and support many birds, reptiles, mammals, and other larger wildlife as food. Even though Pecan trees may not be native throughout the Midwest and Mid-Atlantic; these associated fauna are and can often use Pecan trees as host plants like they would a hickory tree.
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