Wild Boston Fern, Native Sword Fern (Nephrolepis exaltata), Dryopteridaceae Family, native, perennial, evergreen (in areas with no hard freezes)
Range: Florida, Louisiana and Texas south to the Monroe County Keys (where very rare); West Indies, Mexico, Central America and South America.
Wild Boston Fern, Native Sword Fern (Nephrolepis exaltata) is commonly found in swamps and wet hammocks. It can be found growing in moist to seasonally wet, well-drained to poorly-drained soil. The soil can be sandy, limestone or organic with humusy top layer. It also grows epiphytically on Sabal palmetto. It has erect fronds that reach up to 3.5' long and 6" wide with the up to 3" long individual pinnae (leaflets) shallowly toothed, but not divided. The fronds arch with age. The pinnae are slightly curving near the apex with acute to attenuate tips. The basal lobe on the upward facing edge sometimes overlaps the rachis (the axis through the leaf). It is sparsely to moderately scaly near the midvein. The indusia (tissue that covers the spore producing structures) are rounded to horseshoe-shaped. It is one of the most drought tolerant ferns and can withstand brief periods of drought; however, it thrives only under conditions of high humidity. Nephrolepis exaltata is spore-fertile so it can be grown from spores as well as by division.
Wild Boston Fern is primarily recommended for natural landscapes and habitat restorations; however, it has other uses. It is usually grown in moist, shady sites underneath trees or shrubs or as a ground cover. It will spread aggressively by underground runners or stolens if growing in fertile, moist soils. Spreading is less rapid in heavy, clayish soils and areas that are prone to drought. It can be grown Indoors and it is often grown in hanging baskets or on pedestals. When grown in containers, use a pot saucer with a couple inches of pebbles beneath the container. Add water to the saucer to increase humidity. Misting every day or so if the relative humidity is below about 80% will keep it looking its best.
Nephrolepis exaltata should not be confused with Nephrolepis exaltata bostoniensis which is the Boston fern sold as a house plant and whose fronds are broader and droop more. Nephrolepis exaltata has stiffer leaves and fewer leaves and is the original form from which the Boston fern mutated. There are many cultivars of this plant. Tuberous sword fern (Nephrolepis cordifolia) and Asian sword fern (Nephrolepis multiflora) resemble the native sword . Tuberous sword fern is sold under the names Boston fern, hardy fern, large fern and erect sword fern. The names are often interchanged among the different species. Tuberous sword fern usually produces tubers. It is the only one of the four species that is capable of producing them. So, if tubers are present on the plant, it is Nephrolepis cordifolia not Nephrolepis exaltata.
Whisk Fern, Skeleton Fork-fern, Moa (Psilotum nudum) is terrestrial plant that grows in rocky crevices on rocky slopes, low to mesic woods, thickets, swamps and hammocks or as an epiphytic plant (grows on a host, such as a tree, to obtain nutrients). If terrestrial, it is branched and erect; whereas, if epiphytic, it is pendulous. It is classified as a fern ally because it is a spore-producing vascular plant. Thought not to be a true fern, botanists traditionally considered it to be a "primitive" vascular plant. It has only dichotomously branching stems, sporangia and leaf-like enations (lacks true leaves) and lacks roots (like the Bryophytes). It apparently has reduced features from a more complex evolutionary predecessor. Recent molecular genetic research has supported morphological evidence that it probably is a fern of the phylum Pterophyta that has lost many of the pteridophytic characteristics.
Psilotum nudum is propagated by spores or by division at any time of the year. The spores are produced in solitary yellow sporangia which appear on the bract-like or leaf-like lateral appendages. Ripe spores may be sown in the spring. To determine if the spores are ripe, pick a frond and place it in a paper bag. Hang it a room for 24 hours. The spores that fall to the bottom of the bag are ripe and ready to be sown. The spores, which must be kept in the dark, can take up to one year to germinate.
Psilotum nudum occurs as a minor weed in greenhouses seemingly just popping up out of nowhere. I think I have 2 that have come up in 2 different plant containers that I purchased last year. I shall see. It is a really unusual plant and I would love to have at least one.
This fern is commonly known as downy shield fern or downy maiden fern because it is covered with soft hair and has a more or less vertical stature. It can be found growing along roadsides and flood plains, under bridges and in rocky hammocks and moist woods. Although downy maiden fern prefers moist areas, it can grow in dryish, acidic sand. It has a short, stout stem and is 40 to 150 cm tall. The pinnate-pinnatifid blade is 20 to 100 cm long and approximately 25 cm wide. The pinnae (leaflets) are 7 to 17 cm long by about 3 cm wide. They are shallowly cut into blunt, square-shaped lobes. The upper surfaces and lower surfaces are covered in short hairs which give the plant a dull green color and a velvety texture. The lower frond stems lack hairs. Several pairs of the lower pinnae steadily decrease in length toward the base. The fronds that are fertile have longer petioles, the leaflets are closer together and are wider. The sori which are clusters of sporangia (spore-bearing sacs on the underside) are round or kidney shaped. There are 3 to 5 of them that are parallel and on either side of the pinnule (smaller leaflets into which each leaflet is divided) midvein. The base veins of each pair of adjacent pinna (singular for pinnae) lobes unite into one vein which runs to the edge of the pinna, making a triangle; hence, the name tri-vein fern. This is difficult to see with the naked eye.
Thelypteris dentata looks like several other members of its genus; however, the very reduced pair of basal pinnae (the lower leaflets) which causes the frond to have a tapered shape is one identifying feature. The shallowly cut, rounded pinnules (smaller leaflets into which each leaflet is divided) is another distinguishing characteristic.
Chinese Brake Fern, Ladder Brake Fern, Cemetery Fern (Pteris vittata), Pteridaceae Family, naturalized, perennial, can be invasive
A terrestial fern, Chinese Brake has escaped from cultivation. It grows on almost any calcareous substrate, such as old sidewalks, masonry, building crevices, in crevices in limestone rocks, gorges, moist rock walls, streamsides, seeps and nearly every habitat with exposed limestone, notably pinelands in sun or shade (prefers sun). I could not locate any information about its county or regional distribution in Texas. Pteris vittata varies in size, overall color, aspects of the leaf and density of scales on the rachis. Its rhizome is stout, short, creeping and densely covered with matted reddish-brown scales. It has erect or arching fronds. The medium to dull green fronds and pinnules (leaves) are long and tapered giving it an open appearance. The rachis is 4-angled and covered with filiform brownish scales. The fronds 2-8 dm long. The linear-lanceolate, alternate, sessile pinnae (leaflets) are progressively larger from the base of frond to tip and have serrulated margins. They are 6 to 9 mm wide. The terminal pinna is linear-elongate and 5-25 cm long or longer. The veins multi-branched and the sori (are clusters of sporangia) are marginal, linear and continuous.
The problem of arsenic, a heavy metal, in soil is becoming more and more widespread because it is a by-product of many industrial and mining activities and has been a common component of weed killers and pesticides. Extensive research has been conducted and is being done on ways of cleaning soil. Research has found that Pteris vittata has the ability to extract arsenic from soil and store it in its leaves. In fact, most of the references about this fern that I found on the internet refer to this ability. The fern will seek it out and suck up the arsenic even where the arsenic concentration in the soil is low. Once the concentration of the heavy metal in the leaves is high, they can be harvested periodically for disposal in a safe facility. In addition, the ferns can be grown directly the water, similar to the reed-bed systems, where they remove arsenic as well.