10月上旬的太平山步道，樹葉還沒轉金，但北插天山一帶的台灣山毛櫸（Fagus hayatae）已經在悄悄變色。這種殼斗科落葉喬木是冰河時期留下的孑遺植物，依文資法列為珍貴稀有植物，IUCN評為易危，原生於宜蘭南澳、桃園復興、新竹尖石一線的北部稜線，海拔1,300到2,000公尺。太平山官方統計，歷年最佳賞葉期落在10月中旬到11月中旬，寒露這天走進步道，看到的頂多是零星幾片黃邊，主場還沒開始。

節氣名字聽起來像楓紅信號，但翻開物候資料，10月上旬到中旬真正在發生的事，其實更零碎、更安靜。

第一抹紅，不是滿山紅

福壽山、武陵一帶的臺灣紅榨槭（Acer morrisonense）確實從10月中上旬開始轉色，這是台灣特有種，長在中央山脈中海拔1,700到2,900公尺的原始林與次生林裡，塔塔加、新中橫、八通關都能見到。但IUCN把它列為無危，紅皮書也是國家暫無危機，觀察數據誠實地說明了一件事：iNaturalist上台灣使用者記錄「變色葉」的筆數，10月只有4筆，11月飆到19筆，12月更到23筆。寒露那幾天看到的，頂多是第一抹紅，不是滿山紅。大雪山的賞楓要等到11月下旬才輪到它上場。

同一片山林裡，台灣蘋果（Malus doumeri）反而正在結果的高峰。它不是台灣特有種，卻是全島700到2,300公尺闊葉林裡常見的原生種，別名山仙楂、海梨、台灣林檎。8到10月常結實纍纍，果實成熟時紅橙色，直徑約5公分，吸引野鳥、松鼠與台灣獼猴採食。這種果子沒有壯觀的花期或轉色秀，卻是山裡動物寒露前後最直接的食物來源，安靜地撐著整條食物鏈。

河床的假雪，藤蔓上的鐘形花

大安溪河床這時候鋪著一片白，那是甜根子草，8月起抽穗，開花集中在9到10月，遠看常被誤認成芒花海——真正的白背芒芒花海要等到11、12月才登場。兩種草花期錯開一個月，卻常被同一句「賞芒」帶過，其實是不同的植物在不同的時間點各自盛開。

低海拔的路旁林緣，台灣特有種臺灣肺形草（Tripterospermum taiwanense）正好開花，花期9到11月，藤蔓纏繞在草叢或樹幹上，花朵不起眼，得低頭找才看得到。它沒有正式的IUCN評估，紅皮書列為國家暫無危機，算是這批物候名單裡最容易被忽略、卻也最不需要擔心的一種。

菊有黃華，卻只剩一小片岩坡

古代寒露三候有「菊有黃華」的說法，台灣山裡真正對應這句話的植物，是蓬萊油菊（Dendranthema horaimontana）。這是台灣特有種菊科植物，侵限分布在中部山區1,200到1,400公尺的岩生環境，長在陽光充足的岩屑裸露地、碎石坡與岩石隙縫，集中在台中和平（白冷）一帶。一年四季都會開花，秋季開得最茂盛，iNaturalist的觀察紀錄也顯示10月筆數最高。但2017年的紅皮書把它列為國家極危，棲地破碎化是最直接的威脅，主管單位在2022年已著手取種原復育。全台灣能穩定看到它秋季盛花的地方，只剩那幾塊岩坡。

恆春半島同一時間有另一種遷徙在發生：灰面鵟鷹過境，10月上旬到中旬約20天，10月10日前後是重點觀察日，iNaturalist台灣的10月觀察筆數是全年最高。天上的鷹群往南飛，山裡的菊花在岩縫裡開，兩件事看似無關，卻共用同一段節氣時間窗。金蘋果樂園的牧靈人這一季在山裡走動，大概也會遇上它們。

— 溫以君

---

Cold Dew Isn’t About Maple Leaves — It’s When the Mountain Chrysanthemum Blooms

Early October on the Taipingshan trail, the leaves haven’t turned gold yet — but on Beichatianshan, the Taiwan beech (Fagus hayatae) is already quietly starting to change. This deciduous species from the beech family is a glacial relict, listed as a precious and rare plant under Taiwan’s Cultural Heritage Preservation Act and rated Vulnerable by the IUCN. It grows along the northern ridgelines — Nan’ao in Yilan, Fuxing in Taoyuan, Jianshi in Hsinchu — between 1,300 and 2,000 meters. Taipingshan’s own records put peak viewing from mid-October to mid-November. Walking the trail on Cold Dew itself, the leaves are barely edged in yellow. The real show hasn’t started.

That gap is exactly what makes Cold Dew easy to misread. The name sounds like a maple-leaf cue. The actual phenology in early-to-mid October is quieter and more scattered.

First Red, Not Full Red

Around Fushoushan and Wuling, the Taiwan red maple (Acer morrisonense) does start turning from early-to-mid October. It’s endemic to Taiwan, growing in the primary and secondary forests of the central mountain range between 1,700 and 2,900 meters — Tataka, the New Central Cross-Island Highway, Batongguan. The IUCN lists it as Least Concern, no real conservation pressure. But the observation data tells a plainer story: iNaturalist records of “color-changing leaves” in Taiwan show 4 entries in October, jumping to 19 in November, 23 in December. What’s visible around Cold Dew is the first red, not the mountainside on fire. Dajianshan’s maple season doesn’t peak until late November.

In the same forests, Malus doumeri is hitting its fruiting peak. It’s not endemic — a native species found island-wide in broadleaf forest from 700 to 2,300 meters, also known locally as shan-xianzha or hai-li. It fruits heavily from August through October, ripening into orange-red fruit about 5 cm across, drawing wild birds, squirrels, and Formosan macaques. No dramatic flowering or color show — just quiet food supply holding up part of the mountain food chain.

False Snow on the Riverbed, Bell Flowers on the Vine

The Da’an River riverbed turns white this time of year with Saccharum spontaneum, which sends up plumes from August and peaks in bloom September through October — often mistaken for the silvergrass fields that don’t actually peak until November or December. Two different grasses, a month apart, folded into the same casual phrase.

At lower elevations, the endemic Tripterospermum taiwanense is flowering right now — its bloom window runs September to November, vines curling over shrubs and tree trunks, flowers easy to miss unless you look down. No formal IUCN assessment exists for it; it’s the least worrying name on this list.

The Chrysanthemum Blooms, on One Thin Ridge of Rock

Ancient almanacs tied Cold Dew to the line “chrysanthemums bloom yellow.” The plant that actually answers that in Taiwan’s mountains is Dendranthema horaimontana, an endemic species restricted to rocky outcrops between 1,200 and 1,400 meters in central Taiwan, concentrated around Heping (Bailing) in Taichung. It flowers year-round but peaks in autumn — October shows the highest observation count on iNaturalist. Yet the 2017 Red List rated it Critically Endangered, with habitat fragmentation as the direct threat; seed conservation work began in 2022. What’s left, in practical terms, is a handful of rock slopes where it still blooms reliably each fall.

On the Hengchun Peninsula, another migration is underway at the same time: grey-faced buzzards passing through for roughly 20 days in early-to-mid October, with October 10 marked as the peak day. October also shows the year’s highest iNaturalist observation count for the species in Taiwan. Hawks overhead, a critically endangered daisy blooming in a rock crevice — two unrelated events sharing the same narrow window on the calendar.

— 溫以君

延伸閱讀

• 會微笑的兩棲類，住在台灣最冷的地方
• 阿雷塔在東京拿金獎，台灣獨立遊戲的分界點在哪
• 一款全漢字解謎遊戲，接下了櫻井政博的最後一棒
• 國家劇院外牆掛的照片，是六十萬人拍的台灣
• 笠間的土厚，鶯歌的釉薄：兩雙手在轆轤前不說話