Heliamphora nutans

The pitcher plant from Roraima

Heliamphora nutans is the species that founded the genus. George Bentham described it in 1840 from plants that Robert Schomburgk had collected in a marshy savanna on Mount Roraima, at about 6,000 feet (roughly 1,800 m), and placed it in the pitcher plant family, which until then held only Sarracenia ^[3]. WCVP gives the place of publication as the Proceedings of the Linnean Society of London, 1840, and lists Sarracenia nutans as a synonym ^[1].

Bentham described the parts of the trap without accepting what they were for. He noted the dense, thick, reflexed hairs that close the mouth and the smooth, shining zone below them, and found the same structures in Sarracenia purpurea. Writing about the family as a whole, he doubted that catching insects was the pitchers’ main purpose, since a leaf traps only about half a dozen flies or beetles in a season ^[3]. The flowers nod, as the name nutans says: two to six white or pale pink flowers hang from a stalk roughly 30 to 60 cm (1 to 2 feet) tall, each with four to six petal-like segments and 21 to 32 stamens ^[3].

Modern measurements put the pitchers at up to 18 cm tall and 7 cm wide, growing in rosettes at 2,000 to 2,700 m ^[2]. Some lookalikes have been labeled H. nutans by default. Herbarium plants from a tepui in Guyana were identified as H. nutans, probably because it was the only Heliamphora then recognized from that country; they now appear to be a form of H. heterodoxa ^[4]. In Baumgartl’s 1993 key, H. nutans has small anthers (under 4.5 mm) and flower stalks without hairs ^[7].

A trap that works best when wet

Bauer and colleagues dissected H. nutans pitchers from Kew and mapped their zones ^[2]:

1. Nectar is produced on the inner wall and under the small appendage, the nectar spoon, at the back of the mouth.
2. Below the rim, the upper third to half of the inner wall is a dense carpet of inward-pointing hairs. They are about 0.26 mm long near the rim and lengthen to about 1.7 mm at the bottom of the zone.
3. A drainage hole sits near the lower edge of this hairy zone, and below a narrowing the pitcher swells into a smooth-walled bulb that holds the fluid.

The hairs wet so readily that water spreads across them in a film. On a dry pitcher, 29% of visiting ants fell in, most often when they reached the long hairs near the bottom of the zone; after misting, 88% did. Force measurements showed that wetness defeats the ants’ adhesive foot pads, the same aquaplaning trick that the rim of Nepenthes pitchers uses, although the two groups are unrelated. Because the drainage hole sits just above the lower edge of the hairy zone, the hairs wick up fluid from the pool, and the authors propose that this keeps the trap slippery between showers ^[2].

Ants make up much of the catch in the wild, according to Jaffe and colleagues’ field studies ^[12], and they found no digestive enzymes made by the plant in H. nutans fluid ^[13]. The fluid itself is small in volume, about 3.9 mL on average in one set of observations, and its temperature swung from about 9.5 °C in the morning to 19.8 °C at noon ^[13]. The same review notes that Brocchinia, a carnivorous tank bromeliad growing with Heliamphora, takes a broader range of prey ^[13].

On Roraima, food is scarce. Baumgartl found most traps on the Roraima-chain summits holding only rain water, with few insects about ^[7]. Golos and colleagues place H. nutans in a group of Eastern Tepui species, with H. arenicola, H. elongata and H. ionasi, whose retentive hairs, unlike those of most species, do not reflect all colors of light evenly; the four appear to form a single lineage ^[4].

Growing it

The ICPS guide lists the generic selections of H. nutans among the easiest Heliamphora and suggests beginners start with them, along with H. minor, H. heterodoxa and the hybrids ^[10]. Heliamphora became widely available only after clones were propagated in sterile culture in the 1990s, and the guide’s photo of a young H. nutans with its first adult pitcher shows the multiple growth points typical of such plants ^[10]. The genus page covers temperature limits, which matter more than anything else.

Sources disagree on two points:

• How much light. ICPS lists Heliamphora among plants that need intense light ^[8]. João Gabbardo, writing for ICPS from southern Brazil at about 30° S, grew H. nutans alongside Nepenthes, Cephalotus and butterworts under fiberglass roofing that blocked direct sun except in the morning. He concluded the plants can thrive without very high light ^[9]. Weak light does change the plant: in shade, Heliamphora make narrow tubular leaves with a hairless upper interior and a reduced spoon, which Krafft in 1896 called the “assimilation leaves” of H. nutans ^[14]. See the light guide.
• How wet. The ICPS guide’s author kept H. nutans constantly sitting in a few millimeters of water in a 1:1 mix of sand and long-fibered sphagnum ^[10]. Gabbardo used the same 1:1 mix and found the plants tolerate soil that does not drain well ^[9]. Robert Ziemer, growing in live sphagnum in a cool California greenhouse, found that his plants did poorly when waterlogged and preferred to keep them slightly on the dry side ^[11].

The ICPS guide also reports a small fertilizer trial on H. nutans: plants given four slow-release 19-6-12 pellets each were grown beside unfed controls. The author warns that this dose can be too much for some Heliamphora ^[10]. The feeding guide gives the gentler in-pitcher method the guide prefers.

Propagation

• Growing tips. Gabbardo found that a growing tip broken off without roots, pushed into the soil, produced new leaves after one to two months. He recommends this over division because it spares the mother plant ^[9].
• Division. The ICPS guide advises dividing when temperatures are relatively low and bagging divisions for about a month if humidity is below 85% ^[10]. Ziemer had his best results dividing in early summer in his cool climate and lost most divisions made in late fall ^[11].
• Seed. Each H. nutans anther is a tube with pores at its base that releases pollen when a bee vibrates it, which also keeps the pollen dry in rain ^[10]. Ziemer found that H. nutans keeps its stamens even as the ovary swells and gives up pollen when the anthers are lightly teased with a small stick ^[11]. Each stigma is receptive for only two or three days, before its own flower’s pollen is ripe, so the pollen has to go to a newer flower. Seed pods ripen in 6 to 12 weeks, and the seed needs no cold stratification ^[15]. The seed-sowing guide covers the general method.