There is a range of taxa under the name Corybas trilobus, more recently referred to as the Nematoceras trilobum aggregate.

The NZ Plant Conservation Network (http://www.nzpcn.org.nz/) typically has it as "Coastal
to subalpine.

Probably the most widely ranging of all the New Zealand species, occupying a diverse array of habitats from coastal dune forest and scrub to subalpine shrublands and mires".

It becomes necessary then to identify which of these taxa is the original plant described as Nematoceras triloba by JD Hooker in 1853 [1] - which plant is in fact Nematoceras trilobum s.s.
- in the strict sense, sensu stricto.

To make that identification we have to rely on historic documents and herbarium specimens.
Often these are inadequate - the descriptions may have been sufficiently detailed when all members of the aggregate were considered one species, but they do not, nor could they be expected to, differentiate among the separate taxa we recognise today.

The specimens may be dry, colourless and have shrunk in the drying; features obvious in living plants may be lost in the dried or pickled state.

The herbarium sheets may contain more than one collection, and more than one taxon. In that case a taxonomist may designate one of the specimens to be the Type. (Article 9.2 of the Code states, "A lectotype is a specimen or illustration designated from the original material as the nomenclatural type… if no holotype was indicated at the time of publication, or if it is missing,
or if it is found to belong to more than one taxon" [2]).

Sometimes the exact locality of the original collection was not recorded, so we cannot go back
and see what is there today.

All of those issues have hindered the identification of Nematoceras trilobum s.s.

Hooker's Description

The section of the Flora containing JD Hooker's protologue on N. triloba was published in December 1853. Hooker gave the habitat as "Northern and Middle Islands; damp woods.
East Coast and interior, Colenso".

The herbarium sheet for Nematoceras triloba at Kew contains two collections, one from
Cape Palliser, and one labelled "161 Acianthus 1847 Colenso East Coast New Zealand" (below).
Dr Brian Molloy and his colleagues have designated the latter as the lectotype.

Hooker's description reads, "Leaf petiolate, 3/4 inch across, deeply cordato-reniform, trifid,
rarely entire at the point; middle lobe acute. Peduncle shorter than the petiole, often much lengthened when in fruit. Perianth 1/3 inch long; sepals 2 inches; petals half the length of the lateral sepals; upper sepal dilated and retuse at the point. Lip very large, of two parallel recurved lobes, and having two curved ears at the base; margins nearly entire. Column very small."

Much of that applies to several taxa in the aggregate, and in addition Hooker later admitted that some of the plants he described were N. macranthum from the South Island [3]. It is tempting
to suggest the description is thus unreliable - but in fact only the leaf ("rarely entire at the point") suggests N. macranthum.

Where did Colenso find it?

There is convincing evidence that specimen 161 was actually found inland in the Wairarapa
- not on any eastern coast, nor in the South (Middle) Island.

Bruce Hamlin wrote, "Colenso's collecting can be divided conveniently into two periods: (1) the missionary years 1836-52; and (2) the years preceding and including his retirement from 1879-99. … The early years are those of the great journeys: to North Cape, East Cape - Bay of Plenty - Waikato, and then, after his move to Hawke's Bay, the journeys across the Ruahines to Taupo and the bi-annual walks down the Wairarapa Coast to Wellington and back via the Wairarapa valley…. Specimens resulting from these expeditions were numbered and sent to W. J. Hooker at Kew along with voluminous letters listing the numbers and giving localities and other information." [4].

In the letter Colenso sent to WJ Hooker in July 1846 he noted, "161 ?Acianthus, found at last!! detected (leaf only) in 1837 in banks nr the sea, Owae, E. Coast - which spot I often visited but alas! in vain. - and again, (dry capsule) vide, No. 16, "Journal," - and now, in flower, shaded damp spots, wood, with Nos. 154 and 159" [see box].

• Colenso was referring in this note to three separate collections:
• Detected (leaf only) in 1837 in banks near the sea, Owae, E. Coast.
  Again (dry capsule) vide, No. 16, "Journal".
• No. 161, found… now, in flower, shaded damp spots, wood, with Nos 154 and 159.

1. Colenso's "Owae, E. Coast" did not mean East Coast as we know it today: he was in Northland in 1837, relatively untravelled, still awaiting Cunningham's and Hooker's visits, and thus botanically unsophisticated. Owai stream runs to the east coast of Northland at Helena Bay a little south of the Bay of Islands; he had seen only leaves of Nematoceras there (he first visited Owae in February 1836, having walked from Whangaruru). Of his specimen No. 155 in the same package Colenso clearly refers to the east coast of Northland as "E. Coast" [see box]).

2. His second collection was on 6 December 1841 near Tolaga Bay (Uawa river), which he reported in his "Journal of a naturalist" in 1844, "In a wood close by I found an Orchis (16), the leaf of which I had often seen at the northward; but though I had frequently sought its flower, I had never been fortunate enough to obtain it. The flowering season of this, too, unfortunately was long past; I brought away, however, the capsule for examination." [5].

3. Colenso told WJ Hooker that specimen 161 was collected with 154 and 159, and that 154 ("Melicytus") was collected "from forest, hills, between Wareama, & the head of Wairarapa Valley," and 159 from "… woods, with 154."

The other plants with adjacent numbers were found nearby (155 "Wairarapa and elsewhere"; 156 "head of Wairarapa Valley"; 157 "Wairarapa Valley", 158 "in Palliser Bay"; 160 "Wairarapa Valley";
162 "bank of the River Kahumingi, near the wood whence preceding"; 163 ditto [6, and see box].

Thus he collected 162 and 163 on the bank of the Kaumingi, between Whareama and the Wairarapa Valley, near the wood where he collected 161, 154 and 159. He had seen leaves similar to those of 161 nine years earlier in Northland, and dry capsules four years earlier near Tolaga Bay.

Specimen 161 is labelled with a site (East Coast) which is a misreading of Colenso's notes.

When did Colenso find it?

N. trilobum s.l. taxa flower May to December. There is convincing evidence N. trilobum s.s. is a late (October or November) flowering taxon.

Colenso's preceding collection of plants had been sent to Hooker on 19 November 1844, so it is
a reasonable conjecture that he collected specimen 161 between November 1844 and July 1846, when he sent the collection containing specimen 161. There is no evidence that anyone else collected for Colenso in these missionary years [7], so the question becomes, "When was Colenso on the banks of the Kaumingi?"

According to his journals [8], throughout May to October 1845 Colenso was severely ill then later recovering, and from May to July 1846 he was active around the Waitangi mission station at Ahuriri in Hawkes Bay. But on 18 October 1845 he "left… to make (his) half yearly visit throughout the district…."

On 29 Oct he "arrived at Wareama", and on 30 Oct "left this place at xi a.m. Halted at v. p.m., at the entrance of a wood near Kahumingi, very tired and hungry." Then on 31 October "…arrived at Te Kaikokirikiri by 5 p.m." (See Map 1: Te Kaikokirikiri is the site of Masterton, to be founded nine years later).

He continued down the Wairarapa plain to Palliser Bay, thence to Petone and Wellington, returning by the same route in midnovember, via Te Kaikokirikiri on 23 November and Whareama on 25 November 1845, whence out to the coast and on up to the mission station.

He collected specimens numbered 149 to 163 in the Wairarapa, 164-169 from Hawkes Bay, then
a series from Poverty Bay. It is tempting to guess that the numbering follows the collecting sequence; if so 161 would have been collected at Kahumingi on his way home on 24 November.

He probably wrote that excited note ("at last!!") to Hooker soon after he arrived home in December 1845 ("… and now, in flower"), then accumulated further plant specimens, and made further notes, eventually to send all 896 specimens off with his 60 page letter dated July 1846 for shipment.

He added a further 23 specimens, along with hasty notes to Hooker dated 3 August ("I am obliged to write by snatches"), and 22 December 1846 ("My letter to you has been ready for some time past") [9], so they would have arrived at Kew in 1847.

Specimen 161 is labelled 1847 - the year it arrived at Kew, not the year it was collected.

What exactly did Colenso find?

Nematoceras trilobum s.s. must have been a late taxon, flowering on 30 October or 24 November, in the Wairarapa 5 km east of Tauweru on the Masterton Riversdale road, near where it crosses the Kaumingi stream at what is now the Kahumingi Station homestead.

If we ignore the N. macranthum confusion and accept Hooker's description, it had a flower almost 10mm long, sepals 50mm long, flower below the leaf, a notched dorsal sepal and an almost entire labellar edge. It had to be similar enough to N. macranthum (though with "proportionally still longer threadlike lateral sepals and petals) to confuse Hooker at first.

The only Nematoceras I know of that matches those criteria is the late flowering plant tagged N. "Trotters". The specimens on the type sheet also match N. "Trotters" - the flowers are small and shriveled, in some the ovary is swollen, and the largest leaf is 20mm across, but there is no mistaking the habitus, and the long sepals.